Toph, the First Metalbender + Toph, Hardheaded Teacher + Trenching Steed + Arid Archway

Toph, the First Metalbender

Toph, Hardheaded Teacher

Trenching Steed

Arid Archway

How it works

1. Cast the artifact by paying 0.
2. Toph, Hardheaded Teacher triggers, earthbending Arid Archway.
3. Resolve the artifact spell.
4. Activate Trenching Steed by sacrificing Arid Archway.
5. When Arid Archway dies, Toph, Hardheaded Teach triggers, returning Arid Archway from your graveyard to the battlefield tapped.
6. When Arid Archway enters, it triggers, returning the artifact cast in step 1 from the battlefield to your hand, as it's a land due to Toph, the First Metalbender.
7. Resolve the Trenching Steed ability
8. Repeat.

This clever loop turns zero-mana artifact casting into a perpetual motion machine by leveraging Toph, the First Metalbender to fundamentally rewrite your board state, turning every nontoken artifact you control into a land. With Trenching Steed waiting on sacrifice duty, you can feed Arid Archway into its ability for profit; thanks to Toph, Hardheaded Teacher watching from the sidelines, Arid Archway's death immediately triggers its return from the graveyard straight to the battlefield. When Arid Archway re-enters, its own trigger forces you to bounce a land, which can point right back at your newly-landified zero-cost artifact to return it to your hand for another round.