Like possession, but you'd be gone for good, forever?

Wish I could say I'm shocked but I thought it was probably something as bad as this. Just, I've never heard of a spell or rite that works that way. But then he's kind of an expert in reviving obscure magics and twisting them to his own end.

Good thing we've only got one more horcrux to destroy. He won't get an opportunity for his rubbishy "rite."