Toph, the First Metalbender + Umbral Collar Zealot + Encroaching Mycosynth

Toph, the First Metalbender

Umbral Collar Zealot

Encroaching Mycosynth

How it works

1. Cast the earthbending creature by paying its mana cost, causing it to enter as an artifact land creature due to Encroaching Mycosynth and Toph.
2. When that creature enters, it earthbends, causing itself to become a land creature with haste, putting at least one +1/+1 counter on itself, and creating a delayed triggered ability.
3. Activate Umbral Collar Zealot by sacrificing that creature.
4. When that creature dies, the delayed ability from step 2 triggers, causing it to return to the battlefield tapped as an artifact land creature.
5. Repeat from step 2 any number of times.
6. Resolve all activated abilities from Umbral Collar Zealot.