Arkham Knight

The Arkham Knight is the fifth and final boss faced in the main Batman: Arkham Knight mission City of Fear.

Description
The Arkham Knight's boss, taking place in an abandoned mall atrium littered with gargoyles and grates, has four stages; where the Knight is alone, where the Knight has five regular armed soldiers and an electric drone,  where the Knight has six camouflaged soldiers and an electric drone, and where he has two sentries and an electric drone backing him up. The player doesn't have to take down the backup before dealing with the Knight, but it makes everything significantly easier. The Knight himself is permanently perched on a gargoyle armed with a sniper-rifle that does devastating damage (3-4 shots instantly kills Batman) and a sharp eye.

All the player must do is sneak up under him and grapple onto the gargoyle he's on, which activates a small cutscene where a forth of his health is diminished before he escapes to the next stage. Upon retreating, the Knight locks you in said room by lowering the shutter door and releasing gas that will kill Batman in 15 seconds. Just grapple through the small grate in the door to escape. In the forth and final stage, the sentries' pattern is synced in a way that makes it almost impossible to sneak past them and attack the Knight, so it's best to blind one of them with the disruptor and destroy the other one before attacking the Knight.