Frozen Maw fight improvements:
Add giant frost monster minions spawns to the boss part of the fight that target priority on ranged fighters who are standing a certain distance from the boss, and deal increased damage the further they are from the boss. Also with higher HP.
Add Idols to the fight as well that can spawn, and blow up if not destroyed in time, dealing massive damage to players, and healing the boss and his minions half the damage they deal.
During portal fight, what about all the portals beam out magical energy to a center point, spawning a large frozen bone dragon that the Shaman is riding on, and need to be killed for boss to jump off.