The phasing is a pain depending on where people kill him. I have played that game of peekaboo, can see the body, move towards it, body is gone, fly back a bit, body is there, rinse repeat.
I have occasionally dragged another mob as close to the body as I can and killed it to get loot and providing Rukhmar is in range it will pick up the loot off that body too.
I find it’s much better to drag Rukhmar straight down to the ground when he spawns. If he dies on that lump of rock that people like to stand on when camping, it’s often a phasing nightmare.