Things to note:
If you charm the big undead brute, the evasion aura is then on you and your allies, but not your enemies. You can use Dominate Mind (doesn't miss) or a charmed arrow (also did not miss and gave no percentage chance to hit like a regular hit).
Glitter Dust will "cancel out" the evasion capabilities of the big brute so you can bring him down (although, I actually ended up kill him last between freezing him and charming him).
He's undead and heal spells also won't miss, by the way. Nor should Soul Mate and healing yourself.
I could not figure out what was causing the evasion aura at first (it doesn't say "aura" on him) until I charmed him and suddenly my whole party was the one evading.