a moaning banshee  

As noticed above they spawn during the Maestro fight. I think at 50% health. They proc charm, hit for up to 650 and will start to sing a fire resistance song when Maestros HP reach 25% or so, rendering him practically immune to fire which he is very acceptable to first.
Just get some addtanks with decent magic resistance to offtank them and add them some healers, no big deal.

(I might mix them up with the screeching ones, but whatever :P)

Edited, Wed Jun 25 08:11:32 2003