The Sixth Doctor, Ugin's Nexus, Vedalken Mastermind, and Krark-Clan Ironworks

Prerequisites

• The Sixth Doctor on the battlefield
• Ugin's Nexus in hand
• Vedalken Mastermind on the battlefield
• Krark-Clan Ironworks on the battlefield
• Vedalken Mastermind does not have summoning sickness
• each turn available

Steps

1. Cast Ugin's Nexus by paying
2. The Sixth Doctor triggers, copying the Ugin's Nexus spell, with the copy being nonlegendary
3. Resolve both Ugin's Nexus spells
4. Activate Vedalken Mastermind by paying and tapping it, returning the nontoken Ugin's Nexus to your hand
5. Activate Krark-Clan Ironworks by sacrificing the Ugin's Nexus token, adding
6. The Ugin's Nexus token is exiled instead of being put into your graveyard, causing you to take an extra turn after this one
7. Repeat each turn

Results

• Infinite turns