Mob type is definitely undead - Slay Undead procs on these and direct damage to undead also work.
This thing is a pain in the **** to melee because of the voidwalk spell - your only option is to stun as much as you can.
Cheers.
In the Grey: (no data)
In Ssraeshza Temple: (no data)
In Katta Castrum (TBS): (no data)
In Silyssar, New Chelsith: (no data)
In Katta Castrum: Deluge: (no data)