Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight + Vengeful Vampire + Phantom Train

Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight

Vengeful Vampire

Phantom Train

How it works

1. Activate Phantom Train by sacrificing Vengeful Vampire
2. When Vengeful Vampire dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
3. Activate Phantom Train by sacrificing Vengeful Vampire
4. When Vengeful Vampire dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
5. Resolve both Phantom Train abilities from step 1 and 3.
6. Repeat.

This clever loop relies on the constant rebirth of Vengeful Vampire, fueled by the sacrifice outlet built into Phantom Train. Because Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight grants its persist ability to your other nontoken creatures on its back side, the Vampire alternates between returning with a +1/+1 counter from its own undying ability and a -1/-1 counter from persist. Whenever these opposing counters meet, they annihilate each other as a state-based action, resetting the creature's counter tally so it can keep dying and looping indefinitely.