You hit each one twice per round plus the one you are aiming at some extra time. You also iceball them all once per round (when not lagged), and synergy of suffering boosts the damage. Although not a lot.

I basically took the codex at level 36 with tsalantha. Kwoaliki logged on and arrived to finish the prelate off when he was the only one left and was convulsing. I was a sad Panda because I used my only barrier wand to do it, just to see if it could be done.