Karn, Bound by Fate

At the beginning of your end step, if Karn, Bound
by Fate dealt combat damage to one or more
players this turn, restart the game. Then reveal
cards from the top of your library until you reveal
X non-Aura permanent cards, where X is the
amount of damage it dealt to those players. Put
those cards onto the battlefield and the rest on the
bottom of your library in a random order.

Karn, Bound by Fate can’t be your commander.