Graknar the Bull  

He is one of the "slave hunting boar" that will spawn in a random location after you've killed 3 - 5 overseers. He only spawns in this mission. The mission will spawn three "slave hunting boar", more often that not he's in the first or second spawn. His spawn point is random and he will roam around the zone until he finds a slave. If you get the gate potions to the slaves, then he'll eventually path towards zone in of the instance. If you happen to take care of the slaves and then die to him, be prepared, he will be waiting for you when you zone in. That happened to me once, but as he is mezzable - I had zoned in with my bard first and quickly put him to sleep so the rest of the party could zone in and set up safely.