I and my group fought this badboy once..lv 52 necro +pet, lv 55 Enchanter, lv 45 druid and me...lv 25 SK (ok so I was hiding in the back sponging loot)
We were on the wedding floor killing the party and the ushers. Noticed one of the "ghostly ushers" was an "undead usher". No sooner did we lay him out, the enraged relative spawned.
triple 113's and fast as hell, this mother was tough. But in the end, it was dead and we werent ;)