Progenitor Mimic + Walk the Aeons + Timeless Witness

Progenitor Mimic

Walk the Aeons

Timeless Witness

How it works

1. Cast Walk the Aeons 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 Timeless Witness.
3. When the token Timeless Witness enters the battlefield, it triggers itself, returning Walk the Aeons from your graveyard to your hand.
4. Repeat.