Olivia, Mobilized for War + Fecundity + Phantom Train

Olivia, Mobilized for War

Fecundity

Phantom Train

How it works

1. Activate Phantom Train by sacrificing the persist creature.
2. When the persist creature dies, it and Fecundity trigger.
3. Resolve the Fecundity trigger, causing you to draw a card.
4. Resolve the persist creature's trigger, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
5. When the persist creature enters the battlefield, Olivia triggers, putting a +1/+1 counter on the persist creature and causing you to discard a card.
6. Resolve the Phantom Train ability.
7. Repeat.

This clever loop uses Phantom Train as a repeatable sacrifice outlet that feeds your creature back into the graveyard, while Fecundity turns every single trip to the graveyard into a fresh card drawn. The real elegance of the engine lies in Olivia, Mobilized for War: whenever your persist creature returns from the grave, her triggered ability swoops in to place a +1/+1 counter on it. That counter instantly cancels out the creature's -1/-1 counter through state-based actions, resetting its persist ability so it can be sacrificed to Phantom Train all over again.