Eternal Witness + Progenitor Mimic + Time Walk

GU identity

The 3 combo pieces

What must be in place

Enough mana available to cast the extra turn spell each turn.
Progenitor Mimic is a copy of Eternal Witness.

How to execute it

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

What the combo produces