Yeah I posted this during the event before you disavowed them. Why not a paragon Dark Father or two?
A para DF should have lower resists than a Slasher but 50% more HP to compensate, no Crash Ultima spell, but rapid target switching, full necro, and the ability to wreak havoc by spewing lesser undead all over the place.
Sure most of those lesser undead are weak and easily destroyed, but only if someone stops wailing on the boss long enough to destroy them. Otherwise you've got lich lords and rotting corpses hammering on people unopposed.