An opponent controls at least three nontoken creatures that they own and that are not commanders.
({4} magic symbol) available.
Steps
Deal combat damage to an opponent using Etrata, triggering its ability.
Holding priority, activate Lithoform Engine's first ability by paying ({2} magic symbol) and tapping it, copying that ability.
Activate Strionic Resonator by paying ({2} magic symbol) and tapping it, copying Etrata's ability.
Resolve all Etrata abilities, causing you to exile three creatures the opponent controls with hit counters on them, shuffle Etrata into your library, and cause the opponent to lose the game.