Nim Deathmantle, Ashnod's Altar, and Knight of Sorrows

Prerequisites

• Nim Deathmantle on the battlefield
• Ashnod's Altar on the battlefield
• Knight of Sorrows on the battlefield

Steps

1. Activate Ashnod's Altar by sacrificing Knight of Sorrows, adding
2. When Knight of Sorrows dies, its afterlife ability and Nim Deathmantle trigger
3. Resolve the Knight of Sorrows 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 Knight of Sorrows 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