They literally tortured Celyn (almost) to death, because on this side of the Wall it's considered the only way to go to heaven if you have magic and are a human. On the other side, it's really fine, and quite a few people have magic. Tiresius/Keenan/Flynn managed to rescue Celyn at some point, but Celyn asked him to kill him. So he did, because he knew that even with magic there was no way to fix the damage that had already been done.

Ooooh, but it's so much fun! It can be interesting in a not wonderfully good way, but it's still lots of fun to have various things going on! XD