Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight + Strangleroot Geist + Yahenni, Undying Partisan

Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight

Strangleroot Geist

Yahenni, Undying Partisan

How it works

1. Activate Yahenni by sacrificing Strangleroot Geist
2. When Strangleroot Geist dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
3. Resolve the Yahenni ability.
4. Activate Yahenni by sacrificing Strangleroot Geist
5. When Strangleroot Geist dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
6. Strangleroot Geist enters and dies as a state-based action due to having 0 toughness. Its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
7. Resolve the Yahenni ability from step 4.
8. Repeat from step 4.