[brxbrx]

I've done that. "GoR'd" it. It kept my bless, I don't know if it spread my dominion or not, but it did not retain it's priest level. In fact, it was an unmarked champion, and it did not retain any priest level at all.
Maybe if you want to make an SC and have a laugh at your opponent's expense?

Kind of like your own Witch King (LotR). Corrupted to your side, a mockery of humanity.