Toph, the First Metalbender + Haru, Hidden Talent + Firdoch Core + Grinding Station

Toph, the First Metalbender

Haru, Hidden Talent

Firdoch Core

Grinding Station

How it works

1. Cast Firdoch Core by paying 3.
2. When Firdoch Core enters, Grinding Station and Haru trigger.
3. Resolve the Grinding Station trigger, untapping it.
4. Resolve the Haru trigger, earthbending Firdoch Core, as it's a land due to Toph.
5. Activate Grinding Station by tapping it and sacrificing Firdoch Core.
6. When Firdoch Core dies, Haru triggers, returning Firdoch Core from your graveyard to the battlefield.
7. Repeat steps 2 through 4 once.
8. Resolve the Grinding Station ability from step 5.
9. Repeat from step 5.