I still don't understand why Fenrir activates on a new chain after everything finishes and it returns to an open gamestate. If Caius is summoned and I target my opponent's set Trap Hole, I can't ask he waits until the next open gamestate to play the Trap Hole and banish it before he has the opportunity, but if I target my opponent's Kashtira Fenrir, I can. This seems to be the only monster with this effect.