Leonardo, Sewer Samurai + Solemnity + Grinding Station + Ornithopter

Leonardo, Sewer Samurai

Solemnity

Grinding Station

Ornithopter

How it works

1. Activate Grinding Station by tapping it and sacrificing Ornithopter.
2. Cast Ornithopter from your graveyard by paying 0. It will not enter with a finality counter on it due to Solemnity.
3. When Ornithopter enters, Grinding Station triggers, untapping Grinding Station.
4. Repeat.

By leveraging Solemnity, we completely bypass the drawback of Leonardo, Sewer Samurai's graveyard-casting ability, ensuring that Ornithopter never receives a finality counter when it returns from the graveyard for free. Because Grinding Station both sacrifices the Ornithopter and untaps itself whenever an artifact enters the battlefield, you can endlessly loop the thopter from the graveyard back to the battlefield. This self-sustaining cycle feeds Grinding Station's sacrifice trigger indefinitely, milling out your opponents while generating an infinite storm count and endless artifact triggers.