At a guess this mob has about 3-4 times the hitpoints of the 'servants of Mujaki'.
We had four groups, 1 at each gravestone and one roaming to assist when requested. This mob popped with another servant, we called for assist when we realised it wasnt dieing, but we had another round of pops at the same graveyard and had killed all of those pops before this guy was finally dispatched.
Sadly wasnt looted - so no idea if he had anything nice (was too busy beating up Mujaki)