Sorc vs Lucidity Typically as an AP mid you will have access to the blue buff and run 4 points into the sorcery mastery. This gives 24% cdr. In important fights the blue elixir can also be bought. There is currently no AP mid that I would suggest going boots of lucidity for as it is cdr overkill. At end game you end up getting blue buff, blue elixir, sorcery master which is 34% without including items. This in itself makes boots of lucidity not worth it.
CDR Caps at 40% Crest of the Ancient Golem(Blue buff) - 20% Elixir of Brilliance(Blue elixir) - 10% Sorcery(Mastery with max points) - 4%
Extra Common CDR Items Athene's Unholy Grail - 15% Morellonomicon - 20% Deathfire Grasp - 15%
Ionian Boots of Lucidity - 15%
Additionally if you get any of the common AP items that give CDR, you will end up wasting too much stats on Lucidity boots. The only time you should ever get boots of lucidity is when you do not have access to the so called free cdr. This is when you are in the support role. You will typically not have a blue buff, no income from blue elixirs, and may or may not want to run the sorcery mastery.
Only champ I've ever liked having Boots of Lucidity on is Riven. You get your ult back up really quick with the CDR from them and Brutalizer, even at low levels. If you manage to steal their blue (something that's pretty easy if you're top on the purple side), you get up to max CDR. If you're not taking a ton of damage, you won't be needing Merc Treads or Ninja Tabi, anyway.
For mids, you're going to be getting Blue and it+Nashor's/Frozen Heart = 40% CDR and it+Athene's+the Sorcery Mastery = 39% CDR.
Edit: Odd, I didn't think DFG gave CDR anymore.
Generation 30: The first time you see this, copy it into your own signature (on any forum) and add one to the generation number. Social experiment.
I love how this topic assumes every game will go really well and you get exactly what you want every game.
Even if you are being denied blue buff you do not want Lucidity boots. In the case of games where you are behind you are not looking for sustain fights(They have buffs and more damage), you'll have to burst down key champions or catch people out of position(Killing them before they can escape). In these cases you would still stick to sorc boots.^^
Additionally due to the changes in the penetration formula, magic penetration has become much more valuable since percentage magic penetration is calculated before flat magic penetration.