Pattern of Rebirth + Mortuary + Boonweaver Giant + Phantom Train

Pattern of Rebirth

Mortuary

Boonweaver Giant

Phantom Train

How it works

1. Activate Phantom Train by sacrificing Boonweaver Giant.
2. When Boonweaver Giant dies, Mortuary and Pattern of Rebirth trigger.
3. Resolve the Mortuary trigger, putting Boonweaver Giant on the bottom of your library from your graveyard.
4. Resolve the Pattern of Rebirth trigger, putting Boonweaver Giant from your library onto the battlefield.
5. When Boonweaver Giant enters the battlefield, it triggers, returning Pattern of Rebirth from your graveyard to the battlefield attached to Boonweaver Giant.
6. Resolve the Phantom Train ability from step 1
7. Repeat.

This elegant loop begins by leveraging Phantom Train's ability to sacrifice Boonweaver Giant, sending the Giant to the graveyard to feed the engine. As Boonweaver Giant dies, Mortuary ensures the creature immediately returns to the top of your library, while Pattern of Rebirth triggers to tutor that exact same Boonweaver Giant directly back onto the battlefield. This re-entry triggers Boonweaver Giant's ability to seamlessly fish Pattern of Rebirth out of your graveyard and reattach it to itself, resetting the entire chain. By continuously repeating this process, Phantom Train can be fed infinite sacrifices to grow endlessly large while generating an infinite cascade of enter-the-battlefield, leave-the-battlefield, and death triggers.