Progenitor Mimic + Ardent Elementalist + Time Walk

Progenitor Mimic

Ardent Elementalist

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 Ardent Elementalist.
3. When the token Ardent Elementalist enters the battlefield, it triggers itself, returning Time Walk from your graveyard to your hand.
4. Repeat.

This vintage-legal loop achieves infinite turns by turning your upkeep into a recursion engine, anchored by Progenitor Mimic's ability to continually spawn non-token-generating clones of itself. By copying Ardent Elementalist as it enters the battlefield, the resulting token leverages its own enter-the-battlefield trigger to fish Time Walk right back out of your graveyard. Once Time Walk is returned to your hand, you simply cast it again to take another turn, letting the Mimic churn out a fresh Ardent Elementalist each upkeep to sustain the endless cycle.