I was a destroyer, and for the last boss I used my old medic pal in the paladin armor and an assassin. Assuming you have everyone decked out, you also need to be 2 levels higher than that boss so you don't miss him *EVERY SINGLE TIME* with disruption. I used disruption with 1 point, coup with 3, and damage buffs for my assassin and ended up winning. Break helps too. Don't try to do too much damage since you're the only smart one on your team, just control his mana and stun him whenever possible. Also, make sure you have blood focus.
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