Tanthu the Tormentor  

Well, you need to try to keep the three Tormentors within 5% health of each other, but you can't easily move people between them once the fight starts since you'll transfer aggro (and thus AEs) to the other groups. The entire fight you want to compare the health of the three and have people turn off attack if one is getting too far below the others.

For Tanthu the key is to have someone curing disease ASAP to clear the mana drain. Otherwise it's a fairly standard fight. Set a good rampage tank early, heal the main tank and DPS it down.