Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight + Spawning Pit + Stormbound Geist

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

Spawning Pit

Stormbound Geist

How it works

1. Activate Spawning Pit by sacrificing Stormbound Geist
2. When Stormbound Geist dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
3. Activate Spawning Pit by sacrificing Stormbound Geist
4. When Stormbound Geist dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
5. Resolve both Spawning Pit abilities from step 1 and 3.
6. Repeat.