Xartabta  

or maybe that's just because we figured out Aphomat first (see my post).

This time, we tried same strat that worked on Aphomat:

100shm/tank merc, 100 pal/healer merc, 92 pal/wiz merc.

Let the tank roll in and everyone else heal/dps ... much cleaner than the Aphomat fight and no one died!