Toph, the First Metalbender + Toph, Hardheaded Teacher + Lithatog + Rakdos Carnarium

Toph, the First Metalbender

Toph, Hardheaded Teacher

Lithatog

Rakdos Carnarium

How it works

1. Cast the artifact by paying 0.
2. Toph, Hardheaded Teacher triggers, earthbending Rakdos Carnarium.
3. Resolve the artifact spell.
4. Activate Lithatog by sacrificing Rakdos Carnarium.
5. When Rakdos Carnarium dies, Toph, Hardheaded Teach triggers, returning Rakdos Carnarium from your graveyard to the battlefield tapped.
6. When Rakdos Carnarium 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 Lithatog ability
8. Repeat.

This clever loop turns the overlap between land types and artifact types into a self-sustaining engine. With Toph, the First Metalbender turning your nontoken artifacts into lands, a zero-cost artifact functions simultaneously as a land that triggers Toph, Hardheaded Teacher's earthbend ability upon casting. When you sacrifice that same artifact-land to Lithatog, its death triggers Toph to bring it right back to the battlefield. Finally, Rakdos Carnarium's entry trigger conveniently bounces the original artifact back to your hand to be recast, while Lithatog grows infinitely large with every iteration of sacrifices.