Benben said:Mindblank may block most of the lower level enchantment spells, but the higher level enchantment spells aren't all mind effecting (at least in 3.5). Also enchantment is nice enough to give a spell that gives a -10 to will saves, Mind Fog. For a school that is highly dependent on will save this is a nice boon.
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Unless I'm mistaken, all enchantment spells listed in the 3.5PHB are either charms or compulsions (thus, they are all mind-affecting and Mindblank works against all of them.)
However, as hinted by Aust Diamondew above, Greater Dispel Magic can be extremely useful.....
Also, as an aside to the original rant commenting about an 8th level spell giving immunity to all energy attacks, that isn't too far from what is possible. Given an archmage with the Extend Spell feat and the Energy Immunity spell from Tome and Blood, immunity to all energy attacks would cost an 8th level slot, a 7th level slot, and a 5th level slot.