Hound of Griselbrand

Double strike and undying on the same body create a math problem that resolves in the attacker's favor. The first time this dies, it comes back as a 3/3 with a +1/+1 counter, and a 3/3 with double strike trades up against most of what would block it. But the trick is what the counter does to the undying clause itself: undying only triggers when the creature dies with no +1/+1 counters on it. Strip that counter, and the trigger comes back online. Pairing this with something that removes counters (a proliferate-adjacent effect run in reverse, or any way to wipe counters off it) resets the undying loop, and double strike means each iteration is hitting twice in combat. The body is fragile on its face, but the design is built around dying being a downpayment rather than a loss: you are not paying four mana for a 2/2, you are paying four mana for a creature that wants to be killed once and then comes back bigger and still doubling. That asymmetry, where the card's natural recursion is gated by the very counter it gives itself, is the kind of self-limiting loop that keeps it from spiraling without intervention while leaving the door open for any deck willing to do the counter-removal work.