Anti-Venom, Horrifying Healer + Agatha's Soul Cauldron + Triskelion + The Earth Crystal

Anti-Venom, Horrifying Healer

Agatha's Soul Cauldron

Triskelion

The Earth Crystal

How it works

1. Activate Anti-Venom using Triskelion's ability by removing a +1/+1 counter from it, targeting itself and putting two +1/+1 counters on it due to its replacement effect and The Earth Crystal.
2. Activate Anti-Venom using Triskelion's ability by removing a +1/+1 counter from it, dealing 1 damage to any target.
3. Repeat.

By exiling Triskelion under Agatha's Soul Cauldron, you grant its activated ability to any creature you control that holds a +1/+1 counter. Anti-Venom, Horrifying Healer happily takes on this role because its damage-prevention ability turns self-inflicted damage into growth, an effect supercharged by The Earth Crystal to double every counter received into a net surplus. This creates a self-sustaining loop where Anti-Venom continually shoots itself for free, generating infinite counters and infinite damage to close out the game.