Osgir, the Reconstructor, Karn, the Great Creator, Ugin's Nexus, Noose Constrictor, and Kaya, Geist Hunter

Prerequisites

• Osgir, the Reconstructor on the battlefield
• Karn, the Great Creator on the battlefield
• Ugin's Nexus in the graveyard
• Noose Constrictor on the battlefield
• Kaya, Geist Hunter on the battlefield
• Kaya has at least two loyalty counters on it
• available, with an additional every fourth turn available

Steps

1. Activate Kaya's second loyalty ability by removing two loyalty counters from it, causing you to double any tokens you create this turn
2. Activate Osgir by paying , tapping it and exiling Ugin's Nexus from your graveyard, creating four token copies of Ugin's Nexus
3. Put three of the Ugin's Nexus tokens into exile due to the legend rule and their replacement effects, causing you to take three extra turns after this one
4. Activate Karn's first loyalty ability by putting a loyalty counter on it, choosing to do nothing
5. Move to your next extra turn
6. Activate Kaya's first loyalty ability by putting a loyalty counter on it, giving creatures you control deathtouch until end of turn and putting a +1/+1 counter on a creature token you control
7. Repeat from step 4 one additional time
8. Activate Karn's second loyalty ability by removing two loyalty counters from it, returning Ugin's Nexus from exile to your hand
9. Activate Noose Constrictor by discarding Ugin's Nexus
10. Move to your last extra turn
11. Repeat

Results

• Infinite turns