Time Sieve + Mycosynth Lattice + Helm of the Host + Underworld Hermit

Time Sieve

Mycosynth Lattice

Helm of the Host

Underworld Hermit

How it works

1. At the beginning of your combat phase, Helm of the Host triggers, creating at least one token copy of Underworld Hermit with haste.
2. When the Underworld Hermit token enters the battlefield, it triggers, creating at least four 1/1 Squirrel creature tokens.
3. Activate Time Sieve by tapping it, sacrificing the Underworld Hermit token and the Squirrel tokens, causing you to take an extra turn after this one.
4. Repeat each turn.

This clever setup turns a modest insect infestation into an eternal loop by bending the rules of what counts as an artifact. Thanks to Mycosynth Lattice, every single permanent on your battlefield is treated as an artifact, meaning the Squirrel tokens and creatures you generate are suddenly viable fodder for Time Sieve. By equipping Helm of the Host to Underworld Hermit, you guarantee a fresh batch of tokens every single combat step to feed into Time Sieve's sacrifice requirement. As long as your black devotion keeps Underworld Hermit producing enough Squirrels to pay the five-artifact toll, you will chain extra turns indefinitely until your opponents are entirely buried.