So, what I'm gathering here is that RC didn't raise the 3 fake xykons, he "summoned" them.

So then unless xykon were to take the crimson mantle from RC, he can't just put it on any ol'e cleric, and have it work? or could he kill RC and give it to a more naive goblin cleric that would be more willing to aid him, due to naivete?

Basically, an undead cleric is out unless xykon makes an undead goblin cleric or some other rule bending comes into play?