Athreos, Shroud-Veiled, Ugin's Nexus, Xenic Poltergeist, Master Transmuter, and Ashnod's Altar

Prerequisites

• Athreos, Shroud-Veiled on the battlefield
• Ugin's Nexus on the battlefield
• Xenic Poltergeist on the battlefield
• Master Transmuter on the battlefield
• Ashnod's Altar on the battlefield
• Master Transmuter and Xenic Poltergeist do not have summoning sickness
• the first turn, with available each extra turn available

Steps

1. Activate Xenic Poltergeist by tapping it, causing Ugin's Nexus to become an artifact creature until end of turn
2. At the beginning of your end step, Athreos' second ability triggers, putting a coin counter on Ugin's Nexus
3. Activate Ashnod's Altar by sacrificing Ugin's Nexus, adding
4. Ugin's Nexus is exiled instead of being put into your graveyard, causing you to take an extra turn after this one
5. Athreos' third ability triggers, causing you to return Ugin's Nexus from exile to the battlefield
6. Activate Master Transmuter by paying , tapping it and returning Ugin's Nexus to your hand, choosing to not put an artifact onto the battlefield
7. Move to your extra turn
8. Cast Ugin's Nexus by paying
9. Repeat

Results

• Infinite turns