On the opposite side of the room is a generator (glows gold). It's kind of a cylindrical thing on a box. You want to alternate the two different electric shocks to push the giant hook in the middle of the room forward and backward like a swing. Eventually you will send it through the door in the Joker's Mouth. Pull it back out and then grapple up through the new hole.
Fight! If you use the quick shot on the big guy, it will cause a spasm which will swing his hammer in a big circle. Might sound kind of dumb in a 1 on 1 but it's a great way to start the fight. Hit him with that a few times and you should only have 1 or 2 enemies left aside from him. Keep your distance from him and watch for his giant jumping attack. Once it's just the two of you, close in and hit him three times and then double tap the evade button to jump over him. Hit him no more than three times and evade over him again. Rinse and Repeat until he is dead. Climb back up and try again.