Nim Deathmantle, Ashnod's Altar, Xorn, and Prosperous Innkeeper

Prerequisites

• Nim Deathmantle on the battlefield
• Ashnod's Altar on the battlefield
• Xorn on the battlefield
• Prosperous Innkeeper on the battlefield
• available

Steps

1. Activate Ashnod's Altar by sacrificing Prosperous Innkeeper, adding
2. Prosperous Innkeeper dies, triggering Nim Deathmantle, causing you to pay to return Prosperous Innkeeper from your graveyard to the battlefield, and attach Nim Deathmantle to it
3. Prosperous Innkeeper enters the battlefield, creating two Treasure tokens
4. Activate two Treasure tokens by tapping and sacrificing those, adding two mana of any color
5. Repeat

Results

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