Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight + Phantom Train + Clockwork Hydra

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

Phantom Train

Clockwork Hydra

How it works

1. Activate Phantom Train by sacrificing Clockwork Hydra.
2. When Clockwork Hydra dies, its persist ability triggers, returning it from your graveyard to the battlefield without a -1/-1 counter on it due to its replacement effect.
3. Resolve the Phantom Train ability.
4. Repeat.

This clever loop turns Isilu, Carrier of Twilight's passive grant of persist into an engine by using Phantom Train to repeatedly sacrifice Clockwork Hydra. Because Phantom Train's sacrifice ability also buffs itself with a +1/+1 counter while turning into a creature, you can endlessly recycle Clockwork Hydra to generate an arbitrary number of death triggers, enters-the-battlefield events, and massive stat boosts. While Eirdu, Carrier of Dawn isn't directly involved in this specific loop's activation sequence, its front face helps cast your creatures with convoke, rounding out a flexible, transformable package that easily rewards your sacrifices across multiple formats.