Level up the Slow Time spell as high as you possibly can. Wait until the Earth Troll starts spawning there (renown=5 or greater). Then, as soon as the troll starts to come out of the earth, cast Slow Time and start charging your bow. If you've maxed out Slow Time, one charged hit has worked well enough for me in the past. Try to take the shot near the door so that you reduce your risk of getting hit.
here what you do get any bow hide behind the rock near the entrance of the cave. if you have physical Shield turn it on now. if your in the right position you should be able to charge the bow for two minutes while the golem throws rocks on the other side of the boulder. shoot the bow at the golem/troll after two minute charge and it will be a one hit kill and give you a 25x multiplier. Physical shield lets you aim the shot without getting hit. now would also be a good time to use all those ages of whatever potions to get 25000 experience per bottle.
I've seen this somewhere, but I forget, you can get a mercenary, make sure your weapon is weak, like the stick, have the healing life spell and some mana potions are recommended, keep hitting the mercenary or you could just do what they say.
If you can wait until you get ti Witchwood, the rock troll that spawns in the lake can be used.
Go to the demon door, warp to Knothole Glade, walk to Witchwood lake. If he's not there, leave and come back until he is.
Then, hide somewhere that he can't see you. Make sure he is still in the ground, because his throws are abnormally accurate when he can't see you.
After you're hidden, charge up your bow. I charged up an ebony longbow for over 4 minutes, but I think It was a bit of an overkill.
If you did it right, you'll have a 61 multiplier, a dead troll and about 10,000 exp. Then, recall to greatwood caves and run in the demon door with your 30 multiplier before the earth troll can hit you.
go to the hobbe cave and fight your way from the back to the front, make sure you have atleast 20 combat multiplier before you leave because when you exit the cave it halfs itself, so when you get to the troll you should have a combat multiplier of 10ish, kill the troll and its an easy 14 then.
With all the near times I made 14 on the combat multiplier I leveled up my toughness, health, strength and physical shield. Physical shield was a big help but what really did it for me was when I used a crossbow on that troll. As soon as I saw the multiplier hit 14, I talked to the door and then I finished off the troll. Thanks very much for your help.