Etrata, the Silencer + Augmenter Pugilist

Etrata, the Silencer
Augmenter Pugilist

Requires
Etrata on the battlefield. Echoing Equation in hand. You control at least two other creatures that do not have summoning sickness. Etrata does not have summoning sickness. An opponent controls at least three nontoken creatures. 3uu available.
Steps
  1. Cast Echoing Equation by paying 3uu, causing each other creature you control to become a nonlegendary copy of Etrata
  2. Deal combat damage to an opponent with Etrata and two other creatures you control
  3. Etrata and the two creatures trigger
  4. Resolve the first Etrata trigger, exiling a nontoken creature the opponent controls with a hit counter on it, and shuffle Etrata into your library
  5. Repeat step 4 one additional time
  6. Resolve the last Etrata trigger, exiling a nontoken creature the opponent controls with a hit counter on it, shuffle Etrata into your library, and cause the opponent to lose the game
Results
Target opponent loses the game.