Osgir, the Reconstructor + Karn, the Great Creator + Ugin's Nexus + Mondrak, Glory Dominus + Hardened Academic

Prerequisites

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Steps

1. 1Activate Osgir by paying , tapping it and exiling Ugin's Nexus from your graveyard, creating four token copies of Ugin's Nexus.
2. 2Put 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.
3. 3Activate Karn's first loyalty ability by putting a loyalty counter on it, choosing to do nothing.
4. 4Move to your next extra turn.
5. 5Repeat from step 3 one additional time.
6. 6Activate Karn's second loyalty ability by removing two loyalty counters from it, returning Ugin's Nexus from exile to your hand.
7. 7Activate Hardened Academic by discarding Ugin's Nexus.
8. 8Move to your last extra turn.
9. 9Repeat.

Effects

• Infinite turns
• Lock