Instructions
Avoid the Scarecrow's gaze during all three matches. The Scarecrow will constantly be scanning the area for signs of Batman. You will die instantly if the Scarecrow catches sight of you.
Crouch or hide behind whatever objects are present. Use walls, boxes and ledges to conceal your body from Scarecrow's view.
Keep moving forward whenever the Scarecrow is looking away. Use these three to five second windows to move forward as far as you can. For instance, select a wall or box to hide behind that you can make it to in five seconds or less, then run for it whenever the Scarecrow's gaze is averted.
Use your Batgrappler to interact with objects in the environment. For instance, you can pull crates down to hide behind and grapple up to higher locations to reach the spotlight to get past Scarecrow.
Use these tactics during all three fights to eventually defeat the Scarecrow.