Time Sieve + Encroaching Mycosynth + Helm of the Host + Avenger of Zendikar

Time Sieve

Encroaching Mycosynth

Helm of the Host

Avenger of Zendikar

How it works

1. At the beginning of your combat phase, Helm of the Host triggers, creating a token copy of Avenger of Zendikar with haste.
2. When the Avenger of Zendikar token enters the battlefield, it triggers, creating a 0/1 Plant creature token for each land you control.
3. Activate Time Sieve by tapping it and sacrificing five creature tokens, causing you to take an extra turn after this one.
4. Repeat each turn.

This ingenious loop turns a regular combat step into an endless sequence of extra turns by chaining token generation directly into artifact fuel. Encroaching Mycosynth does the heavy lifting behind the scenes, turning all your nonland permanents—including the Plant tokens generated by Avenger of Zendikar—into artifacts so they satisfy Time Sieve's sacrifice requirement. Meanwhile, Helm of the Host provides the engine by churning out a fresh, non-legendary copy of Avenger of Zendikar every single combat phase, which instantly floods your board with enough new tokens to pay Time Sieve's cost and lock down the game with infinite turns.