He flurry and rampages under 15% HP. But without DoT spell, he is still easier than regular vitrik mobs, just has much more HP. He can spawn in any location of vitrik room(pit and side room), and pretty common. Spawned 5 times in 2 hours for us, had both kind of belt/ring and 2 chest essences dropped.
Camping this guy today for the overhaste clicky ring. Some info that isn't mentioned:
CAN be snared. CAN be slowed (slightly was the best I saw) Approx 490K hps Does not flurry, enrage or rampage. Does not cast any spells at all. Does not see invis.
He's actually easier to kill than the regular vitrik mobs, as he doesn't cast that 5K DoT on you. 2 kils so far, didn't get my ring yet though. :(
Found the room he spawns in. It's a room full of vitriks near the hallway that leads outside to where the portals, bazu, Overlord and Grg`nok spawns. Coordinates neg 416 pos 1161. He might be a placeholder for any vitrik but so far he's spawned near the metal torture bed when we got him the first time.
Update: Yeah he spawns in multiple places in the room.
I killed him 5 times today with my 85 paladin and he conned even everytime. His level must be 85, though he hits harder than the yellow con ph's. Also, he dropped phased eternal luminessence twice out of the 5 kills. Maybe wanna add that to the loot list. The slot 3 belt dropped twice, the slot 7-only belt dropped twice and the slot 3 ring dropped once. I'm guessing that makes the ring the uncommon drop.
Veltarik spawns in the vitrik corporifers room. There are 8 spawns total, and in keeping them all dead for a couple hours, I only managed to spawn Veltarik twice. For me, both times he spawned as the roamer pathing north-south through the room. Perhaps he can spawn from any of the eight, dunno ~