Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight, Grinding Station, and Clockwork Hydra

Prerequisites

• Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight on the battlefield
• Grinding Station on the battlefield
• Clockwork Hydra on the battlefield

Steps

1. Activate Grinding Station by tapping it and sacrificing Clockwork Hydra
2. When Clockwork Hydra dies, its persist ability triggers, returning it from your graveyard to the battlefield without a -1/-1 counter on it due to its replacement effect
3. When Clockwork Hydra enters, Grinding Station triggers, untapping Grinding Station
4. Resolve the Grinding Station ability from step 1 Repeat

Results

• Infinite ETB
• Infinite LTB
• Infinite death triggers
• Infinite mill
• Infinite sacrifice triggers
• Infinite self-mill