I tried to Batman it and take everyone out before going for Two-Face, that plan completely backfired since enemies keep on re-spawning. It was pretty annoying considering it's the only part in the game that does that, so I took a more direct approach and just went right at him. All you really have to do is take out the one guy that seems to always be by him, beat him to a pulp, hide and repeat.
It took me several tries but on my final attempt that worked, here's what I did:
I QUICKLY and silently took out every single guard saving the one on the bridge with 2-face for last, and starting with the one guy that's off to the right near you when you begin the room. If you're fast enough, you can be left with 2-face and the one guard on the bridge with 2-face. But it's important to take the guards out quickly enough that another guard doesn't notice a body.
At that point, I waited for 2-face to walk to one to the same side of the bridge as the guard (to make sure I had time to do a take down on the last remaining guard, and reduce the distance between catwoman and 2-face)
While performing that last take down, 2 face will be alerted, and probably get 1 rocket in your face, but at this point you can just use strikes until you send him flying and ready to do more strikes as he gets up.
But the one thing I noticed in the way I did it, was if the guards and 2 face are not aware that you take anyone out, he won't call for reinforcements. But if you try like I did though, you really do have to move quickly to take everyone out to make sure a guard doesn't notice any bodies. I did it in about 1:45, after I engaged the first thug I never stopped moving.
Hope that helps if you or anyone else is stuck, because I had a hard time here too.
Conrad Verner: "My wife was really supportive. She even paid for my shuttle fare off-world." Matriach Aethyta: *facepalm*
If you can take out all the guards except Two Face and the guy right by him without being alerted, you can get on a gargoyle, hit two face with a bola to incapacitate him, and pounce and ground takedown the remaining guy. Then just wail on Two Face until he's dead.
"My oh my, fools aplenty...that includes me, too." Legault, FE7