He isn't so tough. One full group should be enough. There's a ton of aggro in the area (yellow and orange to a fifty) which respawn fast so watch out. After the Green Maw dies he splits into three red. After those die he splits into four orange. After the four orange die he splits into two (I believe two) yellow. You must defeat all of them to complete the quest. He only splits if someone is doing the quest.
skin of a huge koalinth found a bit further then fins :) on top of a kill inside a stone shrine of somekind guarded by grannies and spectral manslayers look out for forest poachers who can pop at trees in front of hill
Enlighter of Chaos proud member of Jupiter, Excalibur/Hibernia