Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight, X-23, Deadly Weapon, and Umbral Collar Zealot

Prerequisites

• Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight on the battlefield
• X-23, Deadly Weapon on the battlefield
• Umbral Collar Zealot on the battlefield

Steps

1. Activate Umbral Collar Zealot by sacrificing the other Mutant
2. When the Mutant dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
3. When the Mutant enters, X-23 triggers, putting a +1/+1 counter on X-23 and the other Mutant
4. Resolve the Umbral Collar Zealot ability
5. Repeat

Results

• Infinite +1/+1 counters on a creature
• Infinite ETB
• Infinite LTB
• Infinite death triggers
• Infinite sacrifice triggers
• Infinite surveil