Underworld Breach, and Grinding Station

Prerequisites

• Underworld Breach on the battlefield
• Grinding Station on the battlefield

Steps

1. Activate Grinding Station by tapping it and sacrificing the artifact with mana value 0, causing you to mill three cards
2. Cast the artifact from your graveyard for its escape cost by paying and exiling three cards from your graveyard
3. When the artifact enters the battlefield, Grinding Station triggers, untapping Grinding Station
4. Repeat

Results

• Infinite self-mill
• Near-infinite storm count
• Near-infinite mana of colors among legendary creatures and planeswalkers you control