Ugin's Nexus + Esoteric Duplicator + Grinding Station

Ugin's Nexus

Esoteric Duplicator

Grinding Station

How it works

1. During your end step, activate Grinding Station by tapping it and sacrificing Ugin's Nexus.
2. Ugin's Nexus is exiled instead of being put into your graveyard, causing you to take an extra turn after this one.
3. Esoteric Duplicator triggers, causing you to pay 2 to create a token copy of Ugin's Nexus at the beginning of your next end step.
4. Resolve the Grinding Station ability, causing target player to mill three cards.
5. Move to your extra turn.
6. At the beginning of your end step, Esoteric Duplicator triggers, creating a token copy of Ugin's Nexus.
7. Repeat.