Practise long ranged duels against Widowmaker as any hero!
Shoot one of 4 different buttons on the door to your left to select the Widow's position. Or you can select the random scene button to randomly select a scene each time you kill the Widow.
Shoot the green button to start the mode and the red button to stop it.
Getting kills refills your health bar.
Press (Interact) to teleport to/from spawn to change heroes.