Nim Deathmantle, Ashnod's Altar, and Syndicate Messenger

Prerequisites

• Nim Deathmantle on the battlefield
• Ashnod's Altar on the battlefield
• Syndicate Messenger on the battlefield

Steps

1. Activate Ashnod's Altar by sacrificing Syndicate Messenger, adding
2. When Syndicate Messenger dies, its afterlife ability and Nim Deathmantle trigger
3. Resolve the Syndicate Messenger trigger, creating a 1/1 Spirit creature token
4. Activate Ashnod's Altar by sacrificing the Spirit, adding
5. Resolve the Nim Deathmantle trigger from step 2, causing you to pay to return Syndicate Messenger from your graveyard to the battlefield, and attach Nim Deathmantle to it
6. Repeat

Results

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