Urza, Prince of Kroog + Turnabout + Encroaching Mycosynth + Archaeomancer

Urza, Prince of Kroog

Turnabout

Encroaching Mycosynth

Archaeomancer

How it works

1. Activate all mana-producing lands you control by tapping them, adding at least 8.
2. Cast Turnabout by paying 2, untapping all lands you control.
3. Activate Urza by paying 6, creating a token copy of Archaeomancer that is a 1/1 Soldier in addition to its other types.
4. When the Archaeomancer token enters the battlefield, it triggers, returning Turnabout to your hand from your graveyard.
5. Repeat.
6. If lands you control can tap to proudce at least 9, this combo nets infinite mana, which can be used to activate Urza's ability infinitely and/or cast Turnabout choosing its other modes.

This intricate loop transforms your entire battlefield into a mechanical playground, relying on Encroaching Mycosynth to turn every nonland permanent you control—including your creatures—into an artifact. With that foundation set, Urza, Prince of Kroog lets you pay six mana to forge a token copy of any of those artifacts, which conveniently makes it a 1/1 Soldier artifact creature. When that engine creates a copy of Archaeomancer, its entry trigger fires to fish Turnabout back out of your graveyard. Finally, casting Turnabout untaps all your lands to feed the cycle anew, netting infinite mana and an army of cloned artifacts as long as your lands produce enough juice.