Time Sieve + Encroaching Mycosynth + Xathrid Necromancer + Maskwood Nexus

Time Sieve

Encroaching Mycosynth

Xathrid Necromancer

Maskwood Nexus

How it works

1. Activate Time Sieve by tapping it and sacrificing five other creatures.
2. When the creatures die as Humans due to Maskwood Nexus, Xathrid Necromancer triggers five times, creating five 2/2 Zombie creature tokens.
3. Resolve the Time Sieve ability, causing you to take an extra turn after this one.
4. Repeat each turn.

This ingenious engine turns an army of fodder into an endless succession of phases by wrapping the battlefield in a clever identity crisis. Maskwood Nexus ensures that every creature you control is a Human, which crucially allows Xathrid Necromancer to trigger whenever those creatures perish and immediately restock your board with five Zombie tokens. Meanwhile, Encroaching Mycosynth quietly transforms all your nonland permanents into artifacts, meaning those very same fresh Zombies—and everything else you own—qualify as the artifact sacrifices required to fuel Time Sieve. By feeding five newly minted tokens to the Sieve each turn, you loop the process indefinitely to take infinite turns, locking your opponents out of the game entirely.