Executed by performing a quarter-circle forward motion and pressing punch, C. Viper performs an electric punch that hits the opponent twice. The distance she moves depends on the punch button that was pressed. The EX variant has her throw two punches. Pressing two punch buttons mid-attack cancels the move, as with the Thunder Knuckle and Seismic Hammer.
The Thunder Fist opens up even more combo opportunities for the already-tricky Crimson Viper.