Nim Deathmantle, Ashnod's Altar, and Merrow Skyswimmer

Prerequisites

• Nim Deathmantle on the battlefield
• Ashnod's Altar on the battlefield
• Merrow Skyswimmer on the battlefield
• available

Steps

1. Activate Ashnod's Altar by sacrificing Merrow Skyswimmer, adding
2. When Merrow Skyswimmer dies, Nim Deathmantle triggers, causing you to pay to return Merrow Skyswimmer from your graveyard to the battlefield and attach Nim Deathmantle to it
3. When Merrow Skyswimmer enters, it triggers, creating a creature token
4. Activate Ashnod's Altar by sacrificing a creature token, adding
5. Repeat

Results

• Infinite ETB
• Infinite LTB
• Infinite death triggers
• Infinite sacrifice triggers