Progenitor Mimic + Time Stretch + Archaeomancer

Progenitor Mimic

Time Stretch

Archaeomancer

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 Archaeomancer.
3. When the token Archaeomancer enters the battlefield, it triggers itself, returning Time Stretch from your graveyard to your hand.
4. Repeat.