Mikaeus, the Unhallowed, Phantom Train, and Grim Poppet

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Phantom Train on the battlefield
• Grim Poppet on the battlefield

Steps

1. Activate Phantom Train by sacrificing Grim Poppet
2. When Grim Poppet 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 LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite -1/-1 counters
• Infinite +1/+1 counters on a creature