Urza, Prince of Kroog + Turnabout + Liquimetal Coating + Archaeomancer

Urza, Prince of Kroog

Turnabout

Liquimetal Coating

Archaeomancer

How it works

1. Activate Liquimetal Coating by tapping it, causing Archaeomancer to become an artifact until end of turn.
2. Activate all mana-producing lands you control by tapping them, adding at least 8.
3. Cast Turnabout by paying 2, untapping all lands you control.
4. Activate Urza by paying 6, creating a token copy of Archaeomancer that is a 1/1 Soldier in addition to its other types.
5. When the Archaeomancer token enters the battlefield, it triggers, returning Turnabout to your hand from your graveyard.
6. Repeat from step 2.
7. 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 loop relies on Liquimetal Coating's ability to turn Archaeomancer into an artifact, making it a valid target for Urza, Prince of Kroog's copying ability. Once Archaeomancer is an artifact, Urza can spend six mana to create a token copy of it, and the token's entry trigger will immediately return Turnabout from your graveyard to your hand. By using Turnabout to untap your lands—assuming they produce enough mana to fund both Turnabout and Urza's activation—you can continuously repeat this cycle to generate infinite mana, infinite artifact creature tokens, and an infinitely large army thanks to Urza's passive anthem boosting all your artifact creatures by +2/+2.