Spark Double, Murderous Redcap, and Ashnod's Altar

Prerequisites

• Spark Double on the battlefield
• Murderous Redcap on the battlefield
• Ashnod's Altar on the battlefield

Steps

1. Activate Ashnod's Altar by sacrificing Spark Double, adding
2. When Spark Double dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
3. As Spark Double enters the battlefield, choose to have it enter the battlefield as a copy of Murderous Redcap with a +1/+1 counter on it
4. When Spark Double enters the battlefield, it triggers, dealing damage equal to its power to any target
5. Repeat

Results

• Infinite colorless mana
• Infinite damage
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers