Invincibility
Note: This procedure involves editing a game file; create a backup copy of the file before proceeding. Use a text editor to edit the "game.erg" file in the "data" folder in the game folder. Remove the hyphen "-" character from the line:

"-BO2 Kain Debug Flags\kain's invulnerable"=1

so it now appears as:

"BO2 Kain Debug Flags\kain's invulnerable"=1

Defeating Faustus
At first, you are in a small circle room with two doors. All you have to do is face the Boss and hold Attack + Block. Wait for him to attack. He has four different types. In the first, he does a five or six hit combo. In the second, he can punch, then kick. In the third, he will just kick. In the fourth, he jumps back with a red glow and lunges forward. When he uses his first type of attack, wait until he punches a third time, then release your block and attack. Repeat this about five times to continue. In the next room you must use the mist form to sneak up to the furnace and burn him. To do this, you must first find the two furnaces with fog in front of them. They are on opposing sides. When you first enter the room, one is to the left and the other is to the right. Run around until he jumps to one of the two, then sneak to the corner and turn mist on. Slowly walk to the switch and fry him. Finally, he will jump around and lunge at you. Just run around until he lunges. This will cause him to eventually fall. Run up to him and use a combo. This must be done about three or four times in order to defeat him.

Keep blocking and sidestepping his attacks while finding open spots for attack until you get about one quarter of his life down. Then, he will run off and enter a room will large heaters and mist around them. When Faustus jumps on to a heater, proceed towards the beginning of the mist trail that leads to the heater and pull the switch to hurt him. Keep repeating this procedure until he jumps up on to a chain, then run to a corner of the room and stay there until Fautus jumps down . He will now try to jump and kick you from far away. If you sidestep his attack, he will hit the wall and will be vulnerable for a few seconds. Keep repeating this until he is dead.

The easiest way to defeat Faustus is to block until your Fury bar glows and hit him with that. Dodge every time you see him try to use a glyph attack. It only takes two Fury hits to get him to go to the furnace room. Load up the Mist glyph and head to a steam spot immediately. You should be able to turn on the furnaces without taking too much damage running from steam spot to steam spot. Once he gets burned and starts running around the rafters, just run around the edges of the room until you hear him drop down. Try to be near a corner or wall. Wait for him to jump at you, then jump or dodge his attack. Once he hits the wall, he will be stunned. You can hit him with a good combo before he jumps back up to the rafters. Repeat this two or three times and he will die quickly.

Defeating Magnus
Magnus is fairly simple to defeat. When he is standing in the middle of the giant fountain that is surrounded by statues, run and hide behind the closest one. He will try to burn you, but will hit the statue. Jump out and shoot him with Telekinesis very quickly. Once he falls into the water, run behind the next statue until he tries to burn you again and repeat the process until he leaves. It should only take three times. In the next room you will see giant statues holding scythes. Magnus cannot burn you anymore, but he will charge into you. Do not bother hitting him. It does not do any good. Get in front of one of these statues and get him to charge you. When he does, dodge him and he will run into the scythe, breaking it. Once it breaks, you will see a glowing telekinetic switch. Jump onto one of the boulders or platforms so Magnus cannot get you, and shoot the switch. The statue will open its arms. Do that to all of the statues and the gigantic statue in the middle of the room will be put back together. Get Magnus to charge into the base of the weapon that the statue is holding the same way as before. When it breaks, make him charge into the base until the statue falls and crushes him. Just stand next to it and shoot Magnus with Telekinesis. That should make him charge you.

Defeating Marcus
You will fight Marcus in a cathedral, on the bottom floor first. On the left and right sides of the room are switches, one on each side. These switches activate bells which disrupt Marcus' concentration and leave him vulnerable for a short time. Hit one switch, then run to the other switch, hitting Marcus on the way. Continue this until his "puppets" disable the bells. Go up to the second floor. Marcus will just run around until you kill him. Use the jump ability to alternate between sides, hitting him on the way. Once he dies, you obtain the Charm ability.

Just hit the bell switches and hit him when he is stunned. When his puppets disable the bell, you can still ring it by jumping into it. He is easier to locate that way. Then, just run around killing enemies while hacking up Marcus, occasionally ringing the bell. You can avoid the puppets altogether, but you will want to build up your Lore bar as much as possible.

Defeating the Sarafan Lord
When the battle starts, the most important thing to do is to locate him. When you do, go to the platform across from him so that there is a walkway between you. When he fires the energy orbs, jump above the first one and stay down on the second. Then, jump again on the third. When he is over you will have seconds to use your Telekenisis on him. When you use it, immediately switch over to jump and knock him off the ledge. You cannot be too close to him when you try to jump or he will teleport away. When he has the Soul Reaver out, switch over to Immolate. He only has one set of attacks. He hits you five times, then uses the magic red sword. Block his five attacks, jump back from the sword, and use Immolate on him. This is the only way to hurt him here. Do this three times to continue. When you get the Soul Reaver, he still has the same attack pattern (five hits then the magic punch). Block the five hits and jump straight up in the air to dodge the red hit. When you get down, immediately use the Soul Reaver. You can only hit him one time per round of attack. It will be awhile before you can defeat him.

When Kain has the Soul Reaver and the Sarafan Lord does the five hits, dodge the magic hammer blow. Then, grab the Sarafan Lord and thrust the Soul Reaver through his chest. You will defeat him in less than a quarter of the time it would take with one hit on each turn.

Once you have obtained the Soul Reaver, build up your special power and use the berserk attack. It will kill him within two hits.

Defeating Sebastian
When the battle starts, run the opposite way of the mist shooting out of the grates. Jump over when needed. Sebastian will not jump, thus burning himself. In his second phase, you must be directly behind one of the mists and follow it around until it stops. When he grabs onto the wall, put the purple portal object between you and him. He will run directly into it. Do this three times to continue. In his third phase, he will try to destroy the stone. Jump up there so he gets off and charm the peasant in the room to unload all of the mist on the ground. His fourth phase is just a fist fight until the finish.

Allow Sebastian to kill you once. Then, allow the game to idle and watch the "steam" appear and kill Sebastian.

Defeating the big mosquitoes
In almost every scene, the enemies have boundaries that they cannot cross. If you find these boundaries, the mosquitoes will be waiting on the opposite side for you to cross back over. Use the jump attack by jumping over and kicking them. Then, before they recover, run back over the boundary line. After four kicks the mosquitoes will die. It is more difficult when there are two waiting for you, but can still be done.