Etrata, the Silencer + Roaming Throne + Lithoform Engine

Etrata, the Silencer

Roaming Throne

Lithoform Engine

How it works

1. Deal combat damage to an opponent using Etrata, triggering its ability twice due to Roaming Throne.
2. Holding priority, activate Lithoform Engine by paying 2 and tapping it, copying either of Etrata's triggers.
3. Resolve all Etrata triggers, exiling three creatures an opponent controls and putting hit counters on them, and then causing that opponent to lose the game.

This assassination loop relies on the unblockable nature of Etrata, the Silencer to cleanly connect for combat damage and trigger her exile effect. With Roaming Throne on the battlefield set to the same creature type, that single combat damage event automatically doubles into two separate exile triggers. We then use Lithoform Engine to copy one of those triggers, bringing the total to three resolved instances. This satisfies Etrata's alternate win condition all in one strike, exiling three of the defending player's creatures and instantly causing them to lose the game.