Time Sieve + Encroaching Mycosynth + Xathrid Necromancer + Xenograft

Time Sieve

Encroaching Mycosynth

Xathrid Necromancer

Xenograft

How it works

1. Activate Time Sieve by tapping it and sacrificing five other creatures.
2. When the creatures die as Humans due to Xenograft, 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 loop turns your regular creature base into a self-sustaining engine for infinite turns, leaning heavily on Encroaching Mycosynth to treat every single nonland permanent you control as an artifact ready to be fed to Time Sieve. To ensure the Sieve always has enough fodder without running out of cards, Xenograft steps in to blanket your entire team with the Human creature type. That type-shifting makes Xathrid Necromancer trigger whenever those creatures are sacrificed, instantly replacing them with five tapped 2/2 Zombie creature tokens to fuel the next iteration of the combo on your extra turn.