Yarus, Roar of the Old Gods + Karlov Watchdog + Switcheroo + Phantom Train

Yarus, Roar of the Old Gods

Karlov Watchdog

Switcheroo

Phantom Train

How it works

1. Donate Karlov Watchdog to an opponent.
2. During the opponent's turn, activate Phantom Train by sacrificing a face-down creature you control.
3. When the creature dies, Yarus's second ability triggers, returning it from your graveyard to the battlefield face-down as a 2/2 creature, and then not turning it face-up due to Karlov Watchdog.
4. Resolve the Phantom Train ability.
5. Repeat from step 2.

This devious loop turns a seemingly harmless swap into an endless cycle of sacrifice and resurrection, utilizing Yarus, Roar of the Old Gods as the core engine that brings your fallen units right back to the battlefield. The trick relies on the clever use of Switcheroo to hand your opponent Karlov Watchdog, whose static ability ensures that when Yarus tries to flip your returning permanents face up, they are forced to stay cloaked face down. From there, Phantom Train serves as the sacrificial outlet that keeps the gears turning, converting your repeated deaths into a mountain of triggers and an infinitely massive Vehicle.