Nim Deathmantle, Ashnod's Altar, and Hallowed Spiritkeeper

Prerequisites

• Nim Deathmantle on the battlefield
• Ashnod's Altar on the battlefield
• Hallowed Spiritkeeper on the battlefield

Steps

1. Activate Ashnod's Altar by sacrificing Hallowed Spiritkeeper, adding
2. When Hallowed Spiritkeeper dies, it and Nim Deathmantle trigger, Resolve the Hallowed Spiritkeeper trigger, creating at least one creature token
3. Holding priority, activate Ashnod's Altar by sacrificing a creature token, adding
4. Resolve the Nim Deathmantle trigger, causing you to pay to return Hallowed Spiritkeeper from your graveyard to the battlefield and attach Nim Deathmantle to it
5. Repeat

Results

• Infinite colorless mana
• Infinite creature tokens
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers