Orvar, the All-Form, Ugin's Nexus, and Capsize

Prerequisites

• Orvar, the All-Form on the battlefield
• Ugin's Nexus on the battlefield
• Capsize in hand
• each turn available

Steps

1. Cast Capsize paying for buyback targeting Ugin's Nexus
2. Orvar triggers, creating a token copy of Ugin's Nexus
3. The token copy of Ugin's Nexus is put into the graveyard due to the legend rule
4. The Ugin's Nexus copy triggers, exiling itself and you take an extra turn after this one
5. Resolve Capsize returning itself and Ugin's Nexus to your hand
6. Pass the turn
7. Cast Ugin's Nexus
8. Repeat

Results

• Infinite turns