Toph, the First Metalbender + Ugin's Nexus + Meticulous Excavation + Grinding Station

Toph, the First Metalbender

Ugin's Nexus

Meticulous Excavation

Grinding Station

How it works

1. Cast Ugin's Nexus by paying 5.
2. When Ugin's Nexus enters, Grinding Station triggers, untapping Grinding Station.
3. At the beginning of your end step, Toph triggers, causing Ugin's Nexus to become an artifact land creature.
4. Activate Grinding Station by tapping it and sacrificing Ugin's Nexus. Ugin's Nexus is exiled instead of being put into your graveyard, causing you to take an extra turn after this one.
5. Toph triggers, returning Ugin's Nexus from exile to the battlefield.
6. When Ugin's Nexus enters, Grinding Station triggers, untapping Grinding Station.
7. Resolve the Grinding Station ability from step 4.
8. Activate Meticulous Excavation by paying 2, returning Ugin's Nexus from the battlefield to your hand.
9. Repeat each turn.