it's way easier using pallies than casters. Never running out of mana and the constant trickle healing is enough. I did this with dk/pally team using a pally as the tank, no healer and it was cakewalk. Went back with druid tank, 3 shammies and a druid healer and couldn't beat it. The adds just kept getting off heals and when magtheridon came i still had 3 spellcasters and a couple infernals up. My casters were pretty oom by then and healer eventually got agro and just went poorly. I might try it again with some rogues or hunters and see if I can develop a second team that isn't so mana dependant.