Yosharian
Arcane
I mean yeah but specifically his ability to continue stripping buffs with no save with each hit, is really nice for this boss fight in particular. And with Prescient Attack + Power of Law that build can basically not missFrankly Aeon needs MR6 for that (as opposed to caster liches, angels and Mobility Trickster, who break the game already at 3-4).Aeon is pretty powerful from that point forward.
Like solve the game powerful.
Though he's no weakling at this point.
Just need to distract him for a few rounds, that's the tricky part