Color Identity: B

Initial Card State
- Walking Ballista in exile (exiled by Agatha's Soul Cauldron).
- Yahenni and Agatha's Soul Cauldron on the battlefield.
Notable Prerequisites
- Yahenni has at least one +1/+1 counter on it.
- You have a way to give Yahenni deathtouch.
Steps
- Give Yahenni deathtouch, if needed.
- Activate Yahenni using Walking Ballista's second ability by removing a +1/+1 counter from it, dealing 1 damage to a creature an opponent controls, and destroying it due to Yahenni's deathtouch.
- Yahenni triggers, putting a +1/+1 counter on it.
- Repeat from step 2 as desired.
- If you can give Yahenni deathtouch indefinitely, you may repeat this loop whenever a creature enters the battlefield under an opponent's control.
Results
- Destroy all creatures opponents control.
- Destroy each creature that enters the battlefield under an opponent's control.
Bracket Tag
This combo has been estimated to be Spicy (Bracket 3-4+).