Mikaeus, the Unhallowed, Phantom Train, and Carnifex Demon

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Phantom Train on the battlefield
• Carnifex Demon on the battlefield

Steps

1. Activate Phantom Train by sacrificing Carnifex Demon
2. When Carnifex Demon dies, its undying ability triggers, returning it from your graveyard to the battlefield without a +1/+1 counter on it due to its replacement effect
3. Resolve the Phantom Train ability Repeat

Results

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