Anti-Venom, Horrifying Healer + Agatha's Soul Cauldron + Triskelion + Primal Vigor

Anti-Venom, Horrifying Healer

Agatha's Soul Cauldron

Triskelion

Primal Vigor

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 Primal Vigor.
2. Activate Anti-Venom using Triskelion's ability by removing a +1/+1 counter from it, dealing 1 damage to any target.
3. Repeat.

This clever loop transforms Triskelion into a self-sustaining engine by letting Agatha's Soul Cauldron grant its activated ability to Anti-Venom, Horrifying Healer, who uses it to shoot itself for zero net loss. Because Primal Vigor doubles the damage-prevention replacement effect into a surplus of +1/+1 counters, you end up with infinite counters to fuel infinite damage to any target. Meanwhile, Agatha's Soul Cauldron also serves as the enabler to exile Triskelion in the first place, while Anti-Venom's entry trigger conveniently ensures you can pull a missing piece right back from the graveyard if needed.