Time Sieve + Encroaching Mycosynth + Helm of the Host + Lena, Selfless Champion

Time Sieve

Encroaching Mycosynth

Helm of the Host

Lena, Selfless Champion

How it works

1. At the beginning of your combat phase, Helm of the Host triggers, creating a nonlegendary token copy of Lena with haste.
2. When the Lena token enters the battlefield, it triggers, creating a number of 1/1 Soldier creature tokens equal to the number of nontoken creatures 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 clever loop relies on Encroaching Mycosynth to turn all your nonland permanents into artifacts, seamlessly bridging your token generation with your extra turn engine. With that foundation set, Helm of the Host equips to Lena, Selfless Champion, churning out a fresh, nonlegendary copy of Lena at the start of every combat phase. Each time that token enters, her triggered ability marshals a squad of 1/1 Soldier tokens from your wide board. Finally, you cash in five of those newly minted artifacts to Time Sieve's activation cost, granting you infinite extra turns while locking your opponents out of the game entirely.