His normal drop is the collar with greater shadowspine rune and a few tradeskill or vendor items. Rare drop is the hammer and rare is the Glowing rune.
I forget the name of it, but the Praetorian Guards in 70.2 cast a buff too that gives them increased resistant to spells. Make sure you dispel this guy before you land debuffs.
i followed him around and never saw him cast bolster. he was casting another spell that seemed to heal/cure him. but he is a roamer, and i caught several bolster messages from some casters immediately as he paused by them in the rooms above the arena. dispell him anyway, regardless of whether or not HE bolsters himself.
also, his roaming path takes him into two hallways where there are no potential adds. one of them is the northwest tunnel leading back to the room south of verok's room, and the other one is the hallway southwest of battlemaster rygosh's spawn point. i prefer to ambush him in the northwest tunnel, but either one would do.
This guy was wandering in the hallways branching NE and NW from the room that is located at about -1550 and +550. Hits just about like any of the trash mobs and dropped the collar, alone for us.