Pokemon Mystery Dungeon:  Red/Blue Rescue Team
Purity Forest Guide
by TwilightPhoenix

--------------------------------
Table of Contents
--------------------------------

1. The Purpose of the Guide
2. Disclaimer
3. What is Purity Forest?
4. How do I prepare?
5. Basic Elements and Strategies
6. Who do I Use?
7. How do I Approach this Dungeon?
8. Other Guides By Me
9. Contact Info
10. Copyrights


--------------------------------------------
The Purpose of the Guide
--------------------------------------------

Pokemon Mystery Dungeon contains one of those challenges that really 
doesn't care how many hours you've put into the game leveling up, 
farming for stat-boosters, seeking out those uber-skills, getting the
best gear, and so forth.  When you present it with all of these impressive
accomplishments, it'll first just laugh at you.  Second, it says come
alone.  When you come back by yourself, it then informs you that your
maxed level, IQ, and stats are worthless, as you'll be reset to a fresh
level one, and it'll destroy any money and items you try to smuggle in.
In other words, Purity Forest is the most difficult dungeon in the game
where there's only two things you can bring with you:  the Pokemon of your
choice and your wits.  

Oh, and you can also bring in a guide, such as this one!  This guide will
attempt to help you through this extremely harsh dungeon with some advice,
strategies, a (mostly theoretical) review of every Pokemon's usefulness in
the dungeon, and one neat little trick I found that made Purity Forest
do a face palm, which is what spurred me to write this in the first place.


--------------------------------------------
Disclaimer
--------------------------------------------

Firstly, this guide makes no guarantee your next run through Purity Forest
will be successful.  This dungeon has a high degree of luck involved in
completing it, which is something this guide is powerless to manipulate.
So hang onto to an Escape Orb if you find one.

Second, it was written with the Red Rescue Team version of the game.  While
I'm pretty darn certain there's no differences between the Red and Blue
versions that'll affect your run through Purity Forest, just in case there
are, I'm disclaiming them.

Finally, some segments of this guide revolve around theory and have not 
been tested.  More than enough has been tried and tested to get you
through, such as the actual strategies.  Now lets be honest here, playing
Purity Forest 300+ times to run through it with every Pokemon, from
Mewtwo to Weedle, just for this guide, which is provided for your viewing
pleasure at no charge, would be asking just a tad bit too much.  However,
the speculative parts are based on raw, hard facts from the game, such as
unmodified leveling stats and what moves a Pokemon can learn.

If you do have tried and tested information in any of the speculative 
parts, feel free to contact me and enlighten me.  You will be credited for
your submissions.


--------------------------------------------
What is Purity Forest?
--------------------------------------------

Some of you may be asking the question that encompasses the title of this
section.  First, Purity Forest hates you.  No matter what you do, it will
not cease to hate you.  And yes, it hates me too.  Second, if you have
not finished the main storyline, go finish it and come back later, Purity
Forest is not available until a little bit after you complete the main
segment of the game.  Third, Purity Forest is what some bits of text in
the game refer to as the "Ultimate Dungeon".  And, with a name like Purity
Forest, you really don't expect it to be until you get a few floors on 
your first try and promptly die.  You'll quickly realize that Purity Forest
is rather deserving of the title and, in fact, puts to shame pretty much
every other game's toughest challenges.  And finally, Purity Forest hates
you.

As for the dungeon itself, Purity Forest is 98 levels of sheer terror, with
the final, 99th floor being home to its primary incentive to do it: 
Celibi.  Upon reaching the 99th floor, you will fight a near impossible
battle against the... wait, wait a second... nevermind, Celibi will offer
to join you without a fight.  Honestly, a boss battle is all Purity Forest
lacks.  However, it's not the number of floors that makes Purity Forest
tough, its the restrictions.  One Pokemon only, reduced to level 1, IQ
set to zero, stats reduced to base, moves set to whatever it knows at level
1.  Additionally, you may not bring any items, you may not bring any cash,
and you may not recruit any Pokemon you beat up.  Whoever you send must be
fully self-sufficient.  Now add the fact that you need some luck with item
spawns (otherwise you might starve or just find useless junk) and scatter
a bunch of traps and the occasional, often mandatory, monster house, and
you have one killer dungeon.  All it lacks is a boss fight.

Is there any other way to get Celibi and just skip the dungeon?  Yes: 
cheat.  And cheating is lame.  Plus there's other incentives to do the
dungeon:  rare items, bragging rights, and the thrill of the challenge.
Especially that first one.  Purity Forest has pretty much every item in the
game that doesn't appear in specific places.  So while you won't find the
Friend Bow, HMs, Keys, evolution items, and so forth, you can find just
about everything else, included the coveted Tight Belt.  It's also the best
source I know for nabbing Sitrus Berries, Joy Seeds, and Life Seeds, enough
so that it can be worth it to just go in, grab as many as you can, and then
flee with an Escape Orb.  And Ginseng isn't that uncommon either.  However,
no gummies will appear, nor Huge Apples (which I find odd), nor other stat
boosters, like Protein.  But still, leaving the dungeon with half an
inventory of the stat boosters it does provide helps everywhere else
except Wish Cave and Joyous Tower (the other two level-one dungeons).

To unlock Purity Forest, first you need to complete the main story.
Afterwards, simply obtain the Sky Blue Plains friend area (it'll be from
a random job offer on the job board or your mail box and can be obtained
before finishing the main story) and save Latias.  And, before someone 
asks, to unlock the mission for saving Latias, you'll need to get the
Southern Island friend area from Wigglytuff and have HM Surf from Solar
Cave (both should be available after clearing the main story).  You'll
then get that mini-story arc the next morning.  For that, see another 
guide, perhaps one of the main walkthroughs.


--------------------------------------------
How do I prepare?
--------------------------------------------

After reading that last section, you may be wondering how could you 
prepare?  Or you may have just overlooked the fact you begin entirely
fresh and clean, completely ignorant of your progress in the game and are
actually wondering how you prepare.  Well, one can get ready for Purity
Forest.  Obviously, this guide will help you handle it (hopefully).
In-game, however, there's two things you can do:  get the Pokemon you want
to send through the nightmarish dungeon and practice.  How do you practice?
You can get an idea of what Purity Forest is like by giving Wish Cave and
Joyous Tower a go.  They're both level one dungeons with less restrictions,
but are still fairly similar in general strategy.  

If you haven't, I recommend running through Wish Cave before attempting
Purity Forest and either demand that Jirachi give you a wish or recruit
him.  The experience will be quite helpful.  Joyous Tower is more optional,
as there's no reason to complete it.  However, it does have some Pokemon
that can only be recruited there, such as Bulbasaur, and the Kecleon shops
do on rare occasions sell Friend Bows.  However, you don't need to do
either before Purity Forest.

Bear in mind, it doesn't matter what the stats are of the Pokemon you are
sending.  A level 1 Rattata will have the same odds of clearing the
dungeon as a level 100 Rattata.  You just need to recruit the Pokemon you
want.  You don't have to do anything else with it beyond that, except
make it your team's leader and ditch everyone else in their Friend Areas.


--------------------------------------------
Basic Elements and Strategies
--------------------------------------------

Obviously, no matter what approach you take or who you send, some things
will hold true and always be helpful.  This section covers those and really
can be read like a list of hints.

First, who should you send?  Obviously someone with a good move pool,
good stats, and a reasonable leveling speed.  You'll want something that
can survive hits (preferably lots of hits) and can dish it out in turn
without having to use items or TMs.  For more specific examples, see the
Pokemon suggestions down towards the bottom.

TMs, what should you watch for?  I've seen every TM down in Purity Forest
except HMs, Hyper Beam, Wide Slash, and Vacuum Cut.  Not to say those won't
appear, I just haven't seen them.  However, there are four in particular
that stand out:  Frustration, Rest, Attract, and Reflect.  With your IQ at
perpetually zero and your level down to 1, Frustration will almost 
certainly be your most powerful attack available for most, if not the
entire, dungeon.  Rest is an excellent healing move, fully recovering you
and curing most status for a mere three turns of vulnerability.  Just do it
when nobody is around.  Attract is an excellent status with a high hit
chance that keeps the target from attacking or moving for several turns,
great for safely defeating it or running away.  And finally, while less
Pokemon can learn it, Reflect helps immensely by cutting all physical
damage in half.  Since most of the damage in Purity Forest is physical,
Reflect is incredibly useful.  Of course, Light Screen also has its uses,
particularly around floors 50-55, since it does the same except for special
damage.  But you'll be hit with physical moves much more often.  These
four should boost your survivability by a great deal should you come across 
them.  

Of the four, however, I'd say Rest is the most important, since Oran
Berries and Reviver Seeds are so dang rare in there and most Pokemon
cannot heal themselves.  Of course, you can get by without Rest just fine.
I completed a run with Espeon in which Rest never showed up, which is when I
discovered Reflect's helpfulness.  Frustration is the next most important
TM.  If you can keep pace or, better yet, stay ahead of the enemy levels,
something I haven't managed to do the entire dungeon yet, your attacks will
do enough damage to make Frustration moot somewhere around floor 50, 
assuming you don't fall behind.  Pokemon with Future Sight can get away
without it since they can use that to set the damage for all of their
attacks to 35, which is slightly weaker than Frustration.  Finally, Attract
and Reflect are the most skippable.  The former because any good status
effect move that keeps you from getting hit, such as sleep, paralyze, or
whiffer, will perform just as well.  The latter because its the least
learned of the four, so most Pokemon have to do without it anyway.

Throwing items:  Gravelrocks and Geo Pebbles are once again useful.  They
each cause a set 20 and 15 damage, respectively, and can be thrown over
walls.  Iron Thorns, Silver Spikes, and Sticks are great too... IF you
have a high enough attack stat.  They're useful early on, but can become
useless later if you're unable to keep your attack paced with the
opponents' defense.  Plus they can only be thrown straight and won't go
through walls, which matters in the last 15 or so floors where ghosts
make an appearance.

What item do you hold?  Lots of possibilities here it really depends on
what you find.  The Power and Special bands work great early on for
causing damage and getting experience faster.  Defense, Zinc, Detect, and
Pass scarves all help you stay alive by helping you reduce or, better yet,
avoid damage.  Of those, I recommend the Pass Scarf the most.  The X-Ray
Specs are nifty, as you can spy all the items and enemies from anywhere.
The Joy Scarf helps you level by giving you experience from damage.  The
Mobile Scarf will let you walk through walls, which is incredibly helpful.
And finally, the Stamina Band and Tight Belt help with belly issues,
allowing you to carry less apples (or worry less about finding apples if
they decide to be scarce).  Everything else should only be used if you have
nothing else or, in some cases (like the Diet Ribbon), not at all.  Though
one could argue that a No-Stick Cap could be quite useful.

Next you have the food issue.  Obviously, you should keep Apples, Big 
Apples, Oran Berries, Max Elixers, and Reviver Seeds, as they help for
hunger and recovery.  Sitrus Berries can be used for healing, but are
better used for increasing your max life or carrying out.  Life Seeds 
should be used right away or smuggled out, same for Joy Seeds, except hold
them if you're about to level.  Ginseng should be saved until you have a
move you want boosted (though don't boost Frustration, it won't do more
than 45 damage) or snuck out.  Totter, Sleep, Allure, and other such
status inducing seeds should be held for throwing at enemies or eating when
you won't get smacked by someone (though don't eat Hunger, Stun, and Doom
Seeds).  Grimy Food should be thrown or eaten by stairs.  Everything else,
like Heal Seeds, Pecha Berries, and so forth can just be munched when
found or carried if you have spare room.

Do pick-up money.  Kecleon shops do appear in Purity Forest with a random
assortment of goods.  What Kecleon sells is mostly junk, but he usually
has one or two items that are helpful (though, on occasion, you'll want
most of his stock).  Plus, you can sell the things you're carrying and
don't need, such as those TMs you can't use.  One nice thing about Purity
Forest is you'll often leave with a nice chunk of cash if you complete it
or use an Escape Orb.  Also, if you're bold, you can rob Kecleon's shop.
Just make sure you know where the stairs are and you have something(s) to
help you get away.  Otherwise Kecleon stands a good chance of just one-hit
killing you.  Oh, and don't try to beat Kecleons with anything that takes
one-hit KOs or the Double Edge Orb.  They're only worth 4 experience
apiece, despite being level 90.  Sigh.

The final item category to consider is orbs.  A lot of orbs have rather
limited usage, like Pounce Orbs, but can save your life in the right
situation.  However, you'll certainly want to carry an Escape Orb if you
find one.  Cleanse Orbs are also good in case you find or have some
sticky items, or step on a sticky trap.  I'd rather carry an extra Cleanse
Orb around rather than wear a No-Stick Cap in Purity Forest since you
really, really need the benefits other hold items give.  Beyond that, 
you'll certainly want one or two "hit the whole room" orbs for those rooms
with lots of pokemon or, worse yet, a monster house.  Petrify Orbs are the
best there, but Slumber, Totter, and Warp also work.  Other orbs that stop
enemies from attacking, like Stayaway and Shock, are worth considering.
The Itemizer and Invisify Orbs are too useful to pass up, but I've only
seen six of those combined in the entire game.  Total.  Be careful
with the One-Room Orb.  It can really help, or really hurt.  If you
use it, pray there's not a monster house on the floor.  Otherwise the
whole floor will become one.  And finally, a Trawl Orb is handy for looting
a monster house without stepping inside it.  Or for robbing Kecleon.  
But only do the latter by the stairs.  Trust me.

Especially in the early floors, you'll want to have Wonder Tiles nearby to
correct your stats.  On the early floors, lots of enemies will lower your
attack and defense, which can seriously hurt you.  Especially Togepi, who
has both Growl and Charm.  Sometimes its better to run from your fight to a
Wonder Tile, even if it gives the enemies free shots on you.  Once you've
explored a floor and decide you want to level up there, camp by the Wonder
Tile closest to the stairs.  Also, moving onto the Wonder Tile in a
monster house is usually a good strategy for helping you clear them if you
can take multiple hits a turn.  Otherwise retreating down the corridor or
shooting off a room-affecting orb is better.

Traps that can really screw you over:  Sticky, Grimy, PP Zero, Block, and,
in some instances, Slow.  Of those, Sticky and PP Zero are the worst
offenders.  Grimy can only mess you up if you don't have much food, and
Block only if you really needed that move then or somewhere else on the
floor.  Whirlwind and Pitfall traps, however, can help you.  The former
sends you flying in a random direction (and will probably do some damage),
which, if you're fleeing foes, can possibly put distance between you and
them.  And if you get dumped in the water and can't go over it, then you'll
warp, which can possibly dump you by the stairs.  The Pitfall Trap works
like an unexpected, forced stairs for five damage.  It can either save
you from enemies or just be convenient to getting to the next floor.  As
traps, however, both can be frustrating if they keep you from doing
something.

Be very, very cautious with taking risks here.  Often, if you don't get 
your gain from a risk, you'll either get seriously hurt or die here.  If
your life is running low, either run or heal.  If those aren't viable,
then whip out that Escape Orb so you'll at least get to keep the stuff you
found.  I've used Escape Orbs on several occasions where I could have taken
chances with my next hit killing the foe, but didn't want to risk their
next hit killing me.  One of those instances let me keep both a Mobile
Scarf and a Tight Belt.

On many floors, you'll find opponents with disproportionate strength
compared to the others.  Sometimes these will be weaker and be easy 
pickings.  But others, like Castform and Eevee when you run into them, are
much tougher without having really any gain over fighting other foes.
Beat them if you can, but approach each new enemy cautiously.  There's
always a toughest foe of any group that can appear on any floor.

Likewise, some foes have higher or lower experience values.  If an enemy
gives you lots of experience, like Exeggcute or, most notably, Skarmory,
Castform, and Electrode, and can be beaten without you getting beaten, go
after them. Skarmory gives the third greatest amount of experience in the
whole dungeon, over 300 when hit with a move and isn't too difficult to
take down.  They spawn around floors 15-17.  Castform offer almost 400 EXP,
but are much stronger and appear on 21-22, 34-38, 54-59, 70-79, and 90-94.
Electrodes spawn around floors 51-53 and are worth over 400 apiece.
However, they are much harder to kill, simply because they have Screech to
annihilate your defenses (couple that with Wonder Tiles becoming more rare
the higher you go) and they have a guaranteed 3-shot kill from
full health with Sonic Boom, which is also a projectile.  How long you can
spend hunting these, Skarmory and Castform on later floors particularly,
will seriously affect your run.  The more you can hunt, the better.  Do
note that by floor 80 there's some high EXP Pokemon as well, like Camerupt,
but these are MUCH stronger than the three mentioned above and may not be
worth hunting, assuming you're strong enough to hunt then at all.

Speaking of experience, the highest level I've managed to hit in Purity
Forest is level 23.  I'm sure 30 is doable and, if reached, should
really make those last twenty floors A LOT easier.  Even my level 23
couldn't fight a battle against more than a couple of foes (or lone, 
specific Pokemon like Parasect) without getting the snot beaten out of her
in return.  Three foes meant she had to flee.  So, again, level up as much
as possible! If you have two or three Big Apples (or even regular apples),
especially if you nabbed a Stamina Band or Tight Belt, you can easily spend
enough time on a floor farming for precious experience points to get the
"Something's stirring..." warning.  

Weather can help or hurt you.  Ground, rock, and steel types can benefit
from the occasional sandstorm that'll show up.  Ice types will like the
Hail.  Everyone else will need to seek cover, including you if you don't
like the damaging weather.  A Weather Band will protect you, but isn't
worth it.  If under damaging weather, keep in mind your level will be too
low to recover health without use of items by just walking or standing. So
do what you can on those floors and get off of them.  But what really 
stinks though is if you enter them with really low health, they could
kill your run right then and there.  Other weather effects are less direct,
take advantage of them if you can (such as hunting down fire types while 
its raining).

Monster Houses.  They're really uncommon, but I can guarantee you'll
encounter at least two, as that's the minimum I've ever seen here.
Also, they're almost always in two very, very important places: rooms
with stairs or the room you appear in on a new floor.  In other words,
they'll be mandatory, so you must have a way to handle them.  As said in
the orbs section, you'll want a room-hitting status orb, preferably 
Petrify.  Other items are also useful, such as Quick Seeds, Invisify Orbs,
and anything else to boost your status.  If you're fortunate to have a
room-hitting move, like Heat Wave, this is the best time to use it.  The
highest floor I've seen a monster house on was in the 90s, so don't be
surprised if they appear as high as 98.  You do have options, however, if
you don't want/can't fight.  You can try to slip by to the stairs or out of 
the room.  Or you can flee back down the corridors you came from and try to
get into the room from another direction.  A Warp Seed is also great for
(hopefully) getting you to safety.

Finally, be aware the difficulty spikes quite a bit often due to the
presence of one or several Pokemon.  Specifically, the difficulty pretty
much doubles after a few floors, though that's not a big deal since the
first few floors are really easy and the experience literally triples.  A
flew floors later, however, Togepi will appear, who can obliterate your
attack power, take one or two too many hits, and hits just a bit too hard.
Skarmory bumps it up a bit around floors 10-15, though you actually need
to hunt down as many metal birds as you can.  In the 30s, the difficulty
takes a sudden jump by introducing Pokemon such as Electrike, who have
enough HP to survive a hit from Frustration and are actually worth less
experience than everything prior except the earliest floors.  Luckily. the
experience more or less corrects itself again by floor 40.  The 50s are a 
bit tough due to a sudden shift in preference to special attacks for a 
brief while, lots of defense droppers (especially through Screech), just
about everything being evolved forms suddenly, and Electrode with his uber-
cheap Sonic Boom.  A lot of Pokemon on those floors use Ember, which for
some reason ignores the Pass Scarf.  If you have Flash Fire, however, those
floors might not be so bad.  The final spike is at floor 80 and stays
through 98.  You'll get attacked by foes who are suddenly much, much
stronger, all around 28-30 it seems based on the damage from Night Shade.
Ghosts will join the fray to hunt you through walls and Parasect will nail
you with Spore and Stun Spore and then murder you with its startling
powerful normal attack and Leech Life.  

To compensate, the Kecleon shops on the final floors tend to carry some
very valuable items.  It's not uncommon to find Sitrus Berries, Life Seeds,
Joy Seeds, Tight Belts, Trap Scarves, etc.  You should have quite a bit of
pocket change by then, so if you run into Kecleon's shop, spend the cash!
Or you could move over to the stairs and use a Trawl Orb...

--------------------------------------------
Who do I use?
--------------------------------------------

I originally was going to include an analysis of every single pokemon, 
but I gave up on that.  It was taking far too long.  So, instead, I'm 
giving some brief suggestions.

In general, you want Pokemon with good stats, particularly defensive, 
and the ability to learn good defensive moves along with a strong attack 
or two.

Starters, particularly evolved ones, and other story-line party Pokemon 
(like Magnemite) start off well and stay relatively strong.  Legendaries 
typically aren't a bad idea, but they tend to level up very slowly.  
Venomoth, while sucky in the higher levels of the main game, is actually 
pretty strong in Purity Forest, particularly since it has Silver Wind from
level 1.  Muk and Grimer also have good stats and excellent damage 
mitigation from abilities and inherent traits.  Lickitung has some great 
stats and a few decent moves, but requires TMs to really shine.  Seadra's 
stats start low but will sky rocket and it has Smokescreen for great 
mitigation.

Ghosts, such as Haunter (he's better than Gengar, believe it or not), 
can hide out in the walls if you can get a Stamina Band, a Tight Belt 
and/or a lot of apples.  Or they can go at it more normally and just use 
the walls as an escape route.

But if you really want a butt-kicking Pokemon, bring Alakazam.  The 
stats will barely rise, but what it starts with at level 1 exceeds what 
most Pokemon can achieve by level 15 or even level 20.  On top of that, 
he can learn very helpful moves like Teleport, Psybeam, Reflect, and 
Recover on his own.

And no, don't bring "lawlz i has wonder guardz" Shedinja.  Despite that
awesome ability, Shedinja is prone to being one-shotted by fire pokemon,
traps, geopebbles, and even the weather.

There's a lot of other pokemon out there that'd probably do pretty 
awesome I didn't even touch in this brief section.  But, I only made 
it to Seaking in my every pokemon analysis and I'm a bit worn on going 
through and evaluating 200 other Pokemon.  Luckily, I was just looking 
at them on paper.  What, you didn't seriously think I've be crazy enough 
to play through Purity Forest 300+ times to test every single pokemon out?


--------------------------------------------
How do I Approach this Dungeon?
--------------------------------------------

At present, I know of four ways to try to tackle this dungeon: fight, 
flight, run through walls, or constant warping.  The last I'll explain 
in a bit in its own dedicated sub-section.  The first two methods are a
bit obvious with the third probably thought up by those who think they're
clever.  And honestly, they are to a degree, but it isn't the most 
difficult solution to the Purity Forest puzzle.

First, fighting.  If you want to fight your way through the entire dungeon,
and you'll want to for at least the first twenty floors, you'll want a
pokemon with great life, lots of defense, lots of attack, and good moves.
This isn't to say special defense and attack are useless, you'll just be
getting hit and using normal attacks more often, aka the standard, 
nameless, typeless weak attack all pokemon have.  Eventually, you'll run
out of PP and Max Elixers (unless you get lucky), so you'll want to be able
to still dish out a reasonable amount of damage by having a good attack
stat.  You'll need to level up as much as possible if you want to fight
all the way through and never quit fighting.  Trust me, you'll need all
the experience you can get to handle those last twenty floors.  The pokemon
on those are beasts.

However, you may not want to fight the whole time, or, despite your best
efforts, Purity Forest just says "Screw you!" and you can't get enough 
levels to keep up.  This is where flight comes in, aka running.  To do 
this, you'll want to be at least level 20 by the upper floors so you can
take a few hits.  Anything that makes you harder to kill is better.  
However, sometimes you'll get stuck being forced to fight, such as pokemon
blocking you on both sides in a corridor.  Having Frustration, Attract, and
Reflect with lots of PP can get you out of these situations.  Otherwise,
you better be ready to use that Escape Orb.

Moving through walls is really an alternative to flight.  You'll want to
level up still, but you won't need to as much.  Mainly because you can't
enter a new floor from within a wall.  And if you spawn into a monster
house, you can still get surrounded.  There's two ways to do this: find
a Mobile Scarf and or be a ghost.  And you'll need lots of food.  This 
isn't perfectly safe since you'll have to risk grabbing items and using
stairs frequently.  Ghosts can make this pretty easy though if they find a
Tight Belt.  Bear in mind, without one, each turn you spend in a wall uses
5 Belly.  As does moving through it from a move like Roar, which really
sucks when that happens.  It's harder to set up for good
effectiveness, but safer if you can do it.

And then there's warping.  A lot of warping.  So much warping you're
doing it every few seconds.  I call it...


-----------THE WARP SCARF METHOD!-----------
*Cue overly dramatic music, glowing lights, and an angelic chorus.*

Ahem!  Anyway, discovering this is what spurred me to write this guide.
This is how I did Purity Forest at a lowly level 12.  A level so low that
the enemies on floor 70+ could pop me in one shot (yay for Reviver Seeds).
This method, borne out of desperation of finding myself under level by
floor 30 and having yet to find a single Frustration TM or having any 
decent attacks with which to easily accumulate experience with, (and
never did find the former), carried me through 70 terror-filled floors in a 
relatively pain-free method. (and let me smuggle out half an inventory of
stat-boosting seeds)  So, how does it work?

It requires some setting up to do, as you do have to find the items.

First, I recommend a Pokemon with good life, defense, and, if you can,
special defense.  Have enough attack or special attack to get yourself to
at least level 10, preferably higher.  Anything lower is seriously
discouraged, as level 12 was low enough for most everything in the higher
floors to two- or three-shot kill me, one-shot against those with super
effective attacks.

Second, you obviously need a Warp Scarf.  That or an absurd amount of
ungodly luck in warping and finding tons of Warp Seeds.  But, considering
that the odds are against you finding enough Warp Seeds to warp yourself
10+ times a floor for 70ish floors (that'd be at least 700 seeds for 70
floors, by the way), you'll need the Scarf.  Kecleon will sometimes
sell them for 50 Poke, and an Itemizer Orb might turn an enemy into one.
Otherwise, you'll have to search for it.

Now, if you were really lucky (or in any other dungeon), that's all you
would need.  But this is Purity Forest we're talking about, the dungeon
that hates you.  So, you'll need some more items in case things don't go so
well, lots of items.  Here's the items I recommend.

1x Warp Scarf
1x+ TM Rests, for healing.
1x+ TM Attracts, for stopping enemies from attacking you.
1x+ TM Reflects, for reducing incoming damage, if your Pokemon can use it.
1x+ Apple or Big Apple in your inventory.  Obviously, you'll need more
eventually.
1x Tight Belt or Stamina Band for walking when its safe, to cut apple usage.
1x Defense hold item.  Pass Scarf, Detect Band, Defense Band, or Zinc Band,
recommended in that order from most to least.  Sometimes you'll need to 
walk near foes or even fight them.
1x+ Reviver seeds.  More is better.
1x+ Max Elixers.  More is better.
1x+ Oran Berries.  In case Rest runs out.
1x+ Status-effect seeds, like Stun Seeds.  In case Attract runs out.
1x+ Room-affecting status orb.  For monster houses, Petrify is the best.
1x+ Cleanse Orb for dealing with Sticky Traps.
1x+ Warp Seeds for on-demand warping out of danger.
1x Escape Orb.  Even if you have all of the above, things can STILL go
wrong in Purity Forest.  This dungeon hates us that much!

Now, normally, the Warp Scarf is a rather useless item.  I mean, when you
have a team following you or, worse yet, an escort, randomly teleporting
every where is not a good idea.  Unless you give your whole team Warp
Scarves because you're bored, then it's amusing.  But, when you're alone
and everyone is out to get you, the Warp Scarf is invaluable for helping
you (eventually) find the stairs.  Yes, it's highly unpredictable, but it
has some guarantees.  First, you'll always warp within five turns after the
last, sometimes immediately.  Second, you only warp into rooms, never
corridors.  And third, warping has a higher priority over enemy movements,
so if you warp, that pokemon next to you cannot hit you.

Whenever you warp, you'll appear in a random spot in a random room (but
never on an item, it seems).  There are some factors to where you go.
First, the bigger the room, the more often you'll appear in it.  Second,
the more rooms there are on a floor, typically the longer it'll take for
you to warp into the room with the stairs and the less likely said room
will have items or pokemon in it.  Hence, if the stairs is in a big room
with few other rooms around, it's likely to be more dangerous but more
profitable if you're nabbing items in the process.  On the other hand,
small room with lots of other rooms, more likely to be safe but bare.

However, because of the Warp Scarf's unpredictability in warping, when you
go for the stairs or an item, you'll want to take it off.  There was a few
times where I forgot, walked onto the stairs, and warped before I could
use them.  On the other hand, you'll grab any item you step on before you
warp.  Generally, when you get onto the stairs, it's a good idea to put
the Warp Scarf back on, in case you spawn next to a foe on the next floor.
If that happens and you're caught without the scarf on, or walking isn't
safe for some other reason, whip out Attract or one of your items to
protect yourself.  Failing that, attack with whatever attack moves you have
(hopefully Frustration). 

But if you do have time to move, either after spawning in or warping next
to enemies, try to walk away from them without cornering yourself.  Keep
in mind you may need up to five turns before you'll warp to another spot,
so try to plan that accordingly and be prepared to drop a status effect or
attack the enemy if you don't warp in time.  Just, whatever you do, don't
surround yourself.  But, if you do, that's where Warp Seeds come in.

When you do get hurt, you can use Rest when you warp to an empty room.
Note that, while resting, you won't be warping at all.  Whether this is a
good thing or not is your personal opinion.  And yes, you will get hurt.
The occasional bad warp, occasional mistake, traps, and enemies with
projectiles will all nail you from time to time.

Now, this method can be viewed as a "cheap" way to get through Purity
Forest, as it is, by far, the easiest approach I've found.  It's great for
those who just want to get through it and grab Celibi.  But for those
looking for a challenge or are masochistic won't find this as fun.
Personally, on any future runs through Purity Forest, I probably won't do
this, as I'm the kind of person who loves the challenge of having to
improvise with whatever you've been given in a difficult situation.  Must
be why I'm drawn to this dungeon...

For trivia, I used a Marowak doing this.


--------------------------------------------
Other Guides by Me
--------------------------------------------

Escape Velocity Nova:  Close Combat Guide -  This is an in-depth guide 
that tells you what ships, weapons, and outfits are good for close 
combat, as well as giving multiple techniques on how to fight at close 
range.

Ares:  Walkthrough -  Contains information on all the races, ships, and
other objects.  It also contains general hints, game basics, single
player walkthrough, and multiplayer hints and level strategies.

Dynasty Warriors 5: Xtreme Legends: Lu Bu -  Contains Lu Bu's move list,
how to use him, how to beat him, his weapon status, recommended item
set-up, and a walk through for his level.

Sonic Adventure 2: Battle: Battle Mode Guide -  Has various strategies for
dominating your friends and rivals alike in the game's multiplayer mode,
whether it be racing, hunting for treasure, shooting each other, playing
an inferior kart mode, or watching cute, cuddly creatures beat the snot
out of each other.


--------------------------------------------
Contact Info
--------------------------------------------

Questions?  Comments?  Did I have incorrect information on something?  
Email me at TwilightPhoenix@gmail.com.  Make sure to have something
like "PKMMD Purity Forest Guide" as the subject.  Also, no attachments
unless I am expecting one from you.  Finally, hate mail will be ignored,
deleted, and blocked.

Also, let me know where you found the guide, especially if you are not on
GameFAQs (www.gamefaqs.com).

--------------------------------------------
Copyright Info
--------------------------------------------

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