Sisyphus, Tortured Soul

Partner with Bouldy, Good Listener (When this creature enters the battlefield, target player may put
Bouldy into their hand from their library, then
shuffle.)
Undying (When this creature dies, if it has no +1/+1 counters on it, return it to the battlefield under its
owner's control with a +1/+1 counter on it.)
Channel — {1}{b}, Discard Sisyphus, Tortured
Soul: Destroy target creature.