Well, if the PCs want to get into nice tight fireball/flamestrike/entange/solid fog/evard's/etc formation... good for the DM. There are plenty of counters to this tactic. If multiple melee fighters in your party want to put points into int and spend two feats to have some very nice AC at the expense of hit mod, points that could have gone into str, dex, or con, and only get the benefit when they are bunched together in melee, I'm sure you can come up with tactics for your NPCs that occasionally reward their character creation choices and occasionally challenge them.
I don't think it is broken. It is very powerful, but also very specialized, and certainly defeatable.
hehe... just thought... toss a level 1 grease spell under them... unless they have 5 ranks in balance... all those dodge bonuses go bye-bye