Etrata, the Silencer, Blade of Selves, Mirror Box, Doubling Season, and Primal Vigor

Prerequisites

• Etrata, the Silencer on the battlefield
• Blade of Selves on the battlefield
• Mirror Box on the battlefield
• Doubling Season on the battlefield
• Primal Vigor on the battlefield
• Blade of Selves attached to Etrata
• Etrata does not have summoning sickness
• An opponent owns at least two cards in exile with hit counters on them
• Each opponent controls at least three nontoken creatures, minus one for each card they own in exile with a hit counter on it

Steps

1. Declare Etrata as an attacker, attacking an opponent that owns at least two cards in exile with hit counters on them
2. Etrata's myriad ability triggers, creating four copies of it attacking each other opponent
3. Deal combat damage with each Etrata, triggering their abilities
4. Resolve the first Etrata ability, causing the opponent dealt damage by it to exile a creature they control with a hit counter on it, and lose the game if they have at least three cards in exile with hit counters on them
5. Repeat step 4 for each remaining trigger

Results

• Each opponent loses the game