Gotta kite him around if he's too buffed, sometimes he'll nuke a party or two and the buff seems to stay on him. We killed him the other night by just kiting him and using enchanter pets periodically
The Cloth Handwraps are no longer available on a vendor (that I could find), but can be looted from an Ultharen Cultist. To make sure you make the killing blow with your main hand that is wearing the wrap, equip a torch in your offhand, or another handwrap. Generic Gadai's won't work, it must be a bandit.
He has:
Localized Storm - puts down a storm on the ground that you have to move out of (looks kinda blue/purple)
Chain Lightning - high shock damage (chains between multiple targets)
Great Storm of the Seer (or something like that) - summons a big blue ogre guy that will cause an AOE knockback. This is the one you really wanna interrupt. It seems you can target the ogre and perhaps attempt to kill it before it does the knockback, but it happens so fast we weren't able to do it.
The ability to buy a potion that gates your group to Barrowdark is actually a pretty cool quest reward. The disguise and signal flare kinda make me think there is a way to continue the quest line as well that hasn't been found yet.
When we did it a person that didn’t have the quest triggered the fight and died and then resurrected him and then the MPC disappeared, and we had the ring
You go into the tower at the top of the stairs in the courtyard of Black Rose keep and there’s a chess or a nightstand next to a bed you click on it a name, guy spawns you Agro him and when he disappears, the ring is in your inventory congratulations. You just finished the most worthless quest in the game.