Darth Vader comes behind them and damages Wedge's ship, forcing him to pull out. Vader then shoots down Biggs.
Luke hears the voice of Obi-Wan telling him to trust his feelings, so Luke switches off his targeting computer. Vader manages to knick Luke's X-Wing, damaging R2.
Right before Vader finishes Luke, Han and Chewie arrive in the Falcon and blast the TIE fighters.
Darth Vader's TIE fighter is ejected from the trench and drifts into space. Luke makes the shot, successfully destroying the Death Star.