Silas Renn, Seeker Adept + Ugin's Nexus + Isochron Scepter + Pull from Eternity + Phantom Train

Silas Renn, Seeker Adept

Ugin's Nexus

Isochron Scepter

Pull from Eternity

Phantom Train

How it works

1. Activate Phantom Train by sacrificing Ugin's Nexus
2. When Ugin's Nexus is sacrificed, it is exiled instead of being put into your graveyard, causing you to take an extra turn after this one.
3. Move to your next turn.
4. Activate Isochron Scepter by paying 2 and tapping it, casting a copy of Pull from Eternity without paying its mana cost.
5. Resolve Pull from Eternity, putting Ugin's Nexus from exile into your graveyard.
6. Deal combat damage to an opponent using Silas Renn, triggering Silas Renn, targeting Ugin's Nexus.
7. Cast Ugin's Nexus from your graveyard by paying 5.
8. Repeat.

This fascinating loop exploits the replacement effect of Ugin's Nexus by using Phantom Train as a convenient sacrifice outlet to exile the Nexus and trigger an extra turn. Once safely in exile, Pull from Eternity—repeatedly recastable courtesy of Isochron Scepter—retrieves the Nexus back to your graveyard. From there, Silas Renn, Seeker Adept steps in, leveraging his combat damage trigger to let you recast the Nexus from the graveyard, setting the whole engine up to go again.