Progenitor Mimic + Ardent Elementalist + Walk the Aeons

Progenitor Mimic

Ardent Elementalist

Walk the Aeons

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