I had to leave at 10% until the boss went down. Other then the orb what else does it drop and does Dreadtooth give you a title for killing him at 10 stacks?
Dread Tooth 10 stack gave us the title of The Resurgent
Dread entity kill gave us teh title of Dread Slayer
Dread Entity single piece of loot was the dreadful orb - we experimented briefly with what it could do and could not figure it out, yet.