Stalwart Successor + Heartmender + Phantom Train

Stalwart Successor

Heartmender

Phantom Train

How it works

1. Activate Phantom Train by sacrificing Heartmender
2. When Heartmender dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. When Heartmender enters, Stalwart Successor triggers, putting a +1/+1 counter on Heartmender
4. Resolve the Phantom Train ability.
5. Repeat.

This crafty loop turns the sacrifice outlet of Phantom Train into an engine for infinite triggers by feeding it Heartmender over and over. When Heartmender goes to the graveyard, its persist mechanic would normally bring it back with a -1/+1 counter that locks it out of future loops, but Stalwart Successor steps in to place a +1/+1 counter on it instead, canceling out the -1/-1 counter entirely due to state-based actions. This delicate balance ensures Heartmender enters the battlefield fresh and ready to be sacrificed again, letting you scale Phantom Train to astronomical heights while generating infinite entry, death, and sacrifice events.