Mikaeus, the Unhallowed + Glen Elendra Archmage + Phantom Train

Mikaeus, the Unhallowed

Glen Elendra Archmage

Phantom Train

How it works

1. Activate Phantom Train by sacrificing Glen Elendra Archmage.
2. When Glen Elendra Archmage 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 Glen Elendra Archmage.
5. When Glen Elendra Archmage 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.