Karn, the Great Creator, Ugin's Nexus, Throne of Geth, and The Chain Veil

Prerequisites

• Karn, the Great Creator on the battlefield
• Ugin's Nexus on the battlefield
• Throne of Geth on the battlefield
• The Chain Veil on the battlefield
• on your first turn, with available each extra turn available

Steps

1. Activate The Chain Veil by paying and tapping it, allowing an extra activation of your planeswalkers' abilities this turn
2. Activate Throne of Geth by tapping it and sacrificing Ugin's Nexus
3. Ugin's Nexus is exiled instead of being put into your graveyard, causing you to take an extra turn after this one
4. Resolve the Throne of Geth ability, putting a loyalty counter on Karn
5. Activate Karn's first loyalty ability by putting a loyalty counter on it, causing a noncreature artifact to become an artifact creature until end of turn
6. Activate Karn's second loyalty ability by removing two loyalty counters from it, returning Ugin's Nexus from exile to your hand
7. Move to your next turn
8. Cast Ugin's Nexus by paying
9. Repeat

Results

• Infinite turns