Progenitor Mimic + Returned Pastcaller + Time Walk

Progenitor Mimic

Returned Pastcaller

Time Walk

How it works

1. Cast Time Walk by paying its mana cost, taking an extra turn after this one.
2. At the beginning of your next upkeep, Progenitor Mimic triggers, creating a token copy of Returned Pastcaller.
3. When the token Returned Pastcaller enters the battlefield, it triggers itself, returning Time Walk from your graveyard to your hand.
4. Repeat.

This vintage loop achieves infinite turns by recycling a single copy of Time Walk through the enter-the-battlefield recursion of Returned Pastcaller. The true engine here is Progenitor Mimic, which anchors the chain by generating a fresh Returned Pastcaller token during every single one of your upkeeps. Because the token is not a copy of a token, Progenitor Mimic's own upkeep trigger sustains the loop indefinitely, letting you recast Time Walk turn after turn until the game is won.