Progenitor Mimic + Ardent Elementalist + Time Warp

Progenitor Mimic

Ardent Elementalist

Time Warp

How it works

1. Cast Time Warp 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 Warp from your graveyard to your hand.
4. Repeat.