Mikaeus, the Unhallowed + Wingrattle Scarecrow + Phantom Train

Mikaeus, the Unhallowed

Wingrattle Scarecrow

Phantom Train

How it works

1. Activate Phantom Train by sacrificing Wingrattle Scarecrow.
2. When Wingrattle Scarecrow dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. Resolve the Phantom Train ability.
4. Activate Phantom Train by sacrificing Wingrattle Scarecrow.
5. When Wingrattle Scarecrow 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.