A fairly straight-forward boss fight consisting of three phases. You can access him via the dungeon finder tool (requires level 89 or above). Once inside, interact with the pumpkin on the alter to begin the fight.
You receive a Loot-Filled Pumpkin on your first kill each day, it can contain the following: Loot-Filled Pumpkin
Every time the boss is killed, one of the following four rings can drop: