Time Sieve + Encroaching Mycosynth + Xathrid Necromancer + Arcane Adaptation

Time Sieve

Encroaching Mycosynth

Xathrid Necromancer

Arcane Adaptation

How it works

1. Activate Time Sieve by tapping it and sacrificing five other creatures.
2. When the creatures die as Humans due to Arcane Adaptation, 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 entire board into an endless engine for infinite turns, sustained by a brilliant web of type-changing rules. Encroaching Mycosynth ensures that all your nonland permanents are artifacts, while Arcane Adaptation names "Human" to paint all your creatures with that vital creature type. This setup means that when you activate Time Sieve by sacrificing five of your creatures, Xathrid Necromancer immediately sees those dying Humans and triggers five separate times. Those triggers flood your board with five tapped 2/2 black Zombie creature tokens, which themselves count as artifacts thanks to the Mycosynth and can be sacrificed to Time Sieve on your next extra turn to repeat the cycle indefinitely.