Mikaeus, the Unhallowed + Phantom Train + Obstinate Gargoyle

Mikaeus, the Unhallowed

Phantom Train

Obstinate Gargoyle

How it works

1. Activate Phantom Train by sacrificing Obstinate Gargoyle.
2. When Obstinate Gargoyle 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 Obstinate Gargoyle.
5. When Obstinate Gargoyle 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.