Agatha's Soul Cauldron + Walking Ballista + Young Wolf

Agatha's Soul Cauldron

Walking Ballista

Young Wolf

How it works

1. Activate Young Wolf using Walking Ballista's second ability by removing a +1/+1 counter from it.
2. Repeat step 1 until Young Wolf has no +1/+1 counters on it.
3. Resolve all Young Wolf abilities dealing 1 damage to Young Wolf, and any remaining damage to any target(s).
4. Young Wolf dies as a state-based action due to having 0 toughness.
5. Young Wolf's undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
6. Repeat.

This loop is a masterclass in turning a humble creature into a lethal weapon using the modular magic of Agatha's Soul Cauldron. By exiling Young Wolf into the Cauldron, its undying ability is granted to Walking Ballista, allowing the Ballista to leverage its own counter-removal to deal damage directly to Young Wolf itself. Once Young Wolf is whittled down to zero toughness and perishes, its undying ability triggers to return it to the battlefield with a fresh +1/+1 counter, resetting the process for infinite damage and triggers.