Progenitor Mimic + Salvager of Secrets + Time Walk

Progenitor Mimic

Salvager of Secrets

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