Saheeli, Radiant Creator, Karn, the Great Creator, Ugin's Nexus, Aether Refinery, and Innkeeper's Talent

Prerequisites

• Saheeli, Radiant Creator on the battlefield
• Karn, the Great Creator on the battlefield
• Ugin's Nexus in hand
• Aether Refinery on the battlefield
• Innkeeper's Talent on the battlefield
• undefined each other turn available

Steps

1. Cast Ugin's Nexus by paying
2. Saheeli's first ability triggers, causing you to get
3. At the beginning of your combat phase, Saheeli's second ability triggers, causing you to pay to create a token copy of Ugin's Nexus that is a 5/5 artifact creature
4. Put the nontoken Ugin's Nexus into exile due to the legend rule and its replacement effect, causing you to take an extra turn after this one
5. Activate Karn's first loyalty ability by putting two loyalty counters on it
6. At the beginning of the end step, Saheeli triggers, causing you to sacrifice the Ugin's Nexus token
7. The token put into exile due to its replacement effect, causing you to take an extra turn after this one
8. Move to your first extra turn
9. Activate Karn's second loyalty ability ability by removing two loyalty counters from it, putting Ugin's Nexus into your hand from exile
10. Move to your second extra turn, and repeat from step 1

Results

• Infinite turns