Was running web lair last night my priest got left behind and died staff of power vanished and nobody claims to have picked it up, searched all around but its not to be found. HashiTashi
If that's the only item that vanished, then someone grabbed it most likely. Nobody is going to fess up if it was on purpose. As has been done with so many other limiteds that have been ganked, it was probably moved to another location so the person who moved it can "find" it later. We'll be looking into some options to deal with this sort of thing soon.