Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight + Spawning Pit + Cayth, Famed Mechanist

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

Spawning Pit

Cayth, Famed Mechanist

How it works

1. Activate Spawning Pit by sacrificing Cayth.
2. When Cayth dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. When Cayth enters, its fabricate ability triggers, putting a +1/+1 counter on it.
4. Resolve the Spawning Pit ability.
5. Repeat.