Stalwart Successor + Trapjaw Kelpie + Yahenni, Undying Partisan

Stalwart Successor

Trapjaw Kelpie

Yahenni, Undying Partisan

How it works

1. Activate Yahenni by sacrificing Trapjaw Kelpie
2. When Trapjaw Kelpie dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. When Trapjaw Kelpie enters, Stalwart Successor triggers, putting a +1/+1 counter on Trapjaw Kelpie
4. Resolve the Yahenni ability.
5. Repeat.

This recursive loop is built around Trapjaw Kelpie entering the battlefield with a persist trigger, only to be immediately fed to Yahenni, Undying Partisan's sacrifice outlet. Every time Trapjaw Kelpie returns from the graveyard with its characteristic -1/-1 counter, Stalwart Successor steps in with its triggered ability to place a +1/+1 counter on it, effectively neutralizing the persist counter through state-based actions. This dance generates an endless cycle of sacrifices, deaths, and entries, fueling Yahenni, Undying Partisan's growth while maintaining an infinite engine.