Nim Deathmantle, Ashnod's Altar, and Iron League Steed

Prerequisites

• Nim Deathmantle on the battlefield
• Ashnod's Altar on the battlefield
• Iron League Steed on the battlefield
• available

Steps

1. Activate Ashnod's Altar by sacrificing Iron League Steed, adding
2. When Iron League Steed dies, Nim Deathmantle triggers, causing you to pay to return Iron League Steed from your graveyard to the battlefield, and attach Nim Deathmantle to it
3. When Iron League Steed enters the battlefield, its fabricate ability triggers, creating a 1/1 Servo artifact creature token
4. Activate Ashnod's Altar by sacrificing the Servo, adding
5. Repeat

Results

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