He is known to be "the demon with a thousand faces" (But very little is know about this monster). Zoralurk has yet never been seen on any Server, but was summoned by customer support on Test Server 2007.
Don't try to go near him unless your level is high (100+ recommended). To kill him, you need a knight with a LOT of hitpoints (at least level 150-180). Furthermore, have as many mages and paladins shoot (power-)bolts and of course SD.
It is useful to have one or more druids heal the blocking knight with Exura Sio all the time, and they could shoot Magic Walls around the knight too so as few summoned Demons as possible will attack the knight.