Nim Deathmantle, Ashnod's Altar, Xorn, and Plundering Barbarian

Prerequisites

• Nim Deathmantle on the battlefield
• Ashnod's Altar on the battlefield
• Xorn on the battlefield
• Plundering Barbarian on the battlefield
• available

Steps

1. Activate Ashnod's Altar by sacrificing Plundering Barbarian, adding
2. Plundering Barbarian dies, triggering Nim Deathmantle, causing you to pay to return Plundering Barbarian from your graveyard to the battlefield, and attach Nim Deathmantle to it
3. Plundering Barbarian 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