Mikaeus, the Unhallowed, Otherworldly Escort, and Phantom Train

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Otherworldly Escort on the battlefield
• Phantom Train on the battlefield

Steps

1. Activate Phantom Train by sacrificing Otherworldly Escort
2. When Otherworldly Escort dies, it triggers, returning itself from your graveyard to the battlefield as a Spirit Detective
3. Resolve the Phantom Train ability
4. Activate Phantom Train by sacrificing Otherworldly Escort
5. When Otherworldly Escort dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
6. Resolve the Phantom Train ability
7. Repeat

Results

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