The circumstances of encountering the boss: You get to fight Bane again in the final battle of the game's campaign mode. You meet him towards the end of your second visit to the Blackgate Prison, after you have reached Joker's hideout, i.e. after the completion of the Stop the Joker #2 - cell block B main mission.
The showdown with Bane consists of two, visible different, phases. Phase one of this fight is very similar to the final phase of the previous meeting with Bane, because he comes already soaked with the Venom and he will be performing formidable charges at you. Remember to avoid Bane's charges at any cost, by performing dodges because, if you are caught by one, you will lose a lot of health points and expose yourself to further attacks. You should also avoid the ground slams (they always end the series of Bane's charges) and the attempts to grab Batman because, in such a situation, you will have to defend yourself against taking heavier damage.
Since you have last fought with Bane at the Gotham Royal Hotel, also tactics of depriving Bane of his health points has not changed. You need to look out for the opportunities to stun the boss with the cape three times (note - Bane can interrupt the cape attacks if you start them too late).
After you have stunned Bane with the cape, start landing quick melee blows that the boss will be incapable of blocking. Round the whole thing up with the special attack initiated by pressing two keys/buttons at the same time (this is not required, but will allow you to deplete the boss' healthbar faster).
From the moment in which you land one whole series of attacks, there will appear inmates in the arena. Do not ignore them entirely although you may count on the fact that many of them will be swept off their feet with Bane's attacks. It is much better an idea to use them to charge the shock gloves. As you can probably remember, the gloves will help you weaken the boss so, it is worthwhile to activate them as soon as they are available.
After you have depleted around 1/3 of Bane's health, the game will play a cutscene featuring Joker, Captain Gordon and the Prison Warden Joseph. From now on, the shock gloves will remain active until you have completed this phase of the fight so, you can start ignoring Bane's men on a larger scale. You still need to avoid the boss' charges and wait for opportune moments to launch your offensive. (cape- beatdown - the special button combination).
Continue fighting until the moment when Bane has only a small portion of health left. The game should soon play another cutscene, after which you need to reanimate Bane so, at the appropriate moments, press the standard attack key/button. After several moments, the second phase of the fight will start, where you will have to face off against the heavily-mutated Bane.
The second phase of the battle requires a completely different approach. Do not attempt any frontal attacks on the boss because, not only will it end in a failure, but also you will be grabbed by Bane and lose some of your health, as a result. Avoid detection for the whole time and, if you are spotted, start running and, of necessary, use additionally a smoke pellet that will blind Bane, or a glue grenade, to stop him for a moment. It is a good idea to use the detective vision, on a regular basis, to determine the boss' current position and adjust the strategy.
The good news is that you do not need to use the main corridors only, because you can just as well hide in venting shafts that surround the entire area, and run under the floor. Batman will not have to lose time to rip the grates off the walls. What is even more, while escaping from Bane, you can perform a slide towards a side-shaft, which considerably diminishes the risk of being caught.
The venting shafts are a geed way to avoid Bane and plan on further attacks although, you cannot feel completely safe there. In the case of the side-shafts, try to get away from their exits and, in the case of the lower shafts, use mainly the places where the camera changes its position into the first-person mode. The reason is that Bane will be searching the shafts on a regular basis and lift/rip off the grates, especially right after a successful escape.
There are two different ways in which you can deal damage to Bane. Variant one assumes that you sneak up to Bane from behind and press the quiet takedown key/button. Batman will then jump onto the boss and direct him towards the nearest wall. Unfortunately, as a result of this type of attacks, Bane will not lose too many health points.
Variant two is way better, and it assumes that you keep pushing Bane onto the electric fence that separates the cages with prisoners from the main corridors. Hide in a lower shaft, close to one of such fences and wait for the boss to appear around (screenshot 1). Press the attack key/button, combined with dashing out of the shaft, and start landing a series of quick blows (screenshot 2). The correct execution of all the actions, should result in Bane's losing many more health points.
Regardless of the tactics, you need to cause the boss to lose nearly all of his healthpoints. Watch a stunning cutscene and use the grapple twice, on the anchor points that the game points you to, to extend the rope and defeat bane definitively.