Time Sieve, Encroaching Mycosynth, Xathrid Necromancer, and Arcane Adaptation

Prerequisites

• Time Sieve on the battlefield
• Encroaching Mycosynth on the battlefield
• Xathrid Necromancer on the battlefield
• Arcane Adaptation on the battlefield
• You control at least five other creatures
• "Human" chosen with Arcane Adaptation

Steps

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

Results

• Infinite turns