[The Ozzman]

if youre having problems with the really big one in the room where they are guarding the weapons, give your best tank all ur best AC lowering equipment. Helm of Balduran, Fortrees shield, ring of eart control, and cast defensive harmony. Then have that tank take him on 1on 1 you should be able to take him out. Due it at the entrace to the room and have a healer standing to the right of your fighter. Just run when he spouts off his gas.