Progenitor Mimic + Time Stretch + Returned Pastcaller

Progenitor Mimic

Time Stretch

Returned Pastcaller

How it works

1. Cast Time Stretch by paying 8, taking two extra turns 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 Stretch from your graveyard to your hand.
4. Repeat.

This ingenious loop lets you seize infinite turns by cycling Time Stretch right back to your hand every single cycle. The engine gets its momentum from Progenitor Mimic, which establishes a steady rhythm by churning out fresh tokens of whatever creature you need during each of your upkeeps. When those upkeeps roll around, the Mimic reliably spawns a copy of Returned Pastcaller, whose entry trigger plucks Time Stretch straight out of your graveyard and puts it ready to cast again. It is a brilliant display of recursive mastery—turning a massive extra-turn spell into an endless procession of days.