You start in a tiny 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 proceed. 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. Lastly, 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.
-Always block and sidestep his attacks while finding open spots for attack until you get about one quarter of his life down. He will then 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 several 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. Evade 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 right away. 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 evadee 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.
-At the start, equip your Fury power, block his combos, and back up when you see him charge up with a red attack (which is unblockable). Try to get some hits in, then use Fury when it is charged up. You will then enter a room with four furnaces. Luckily one furnace has mist that flows close to the center of the room. Chase him around until he is on top of that furnace. Then, without getting too close to it, use the Mist power, and activate the furnace. You will need to do this about three to four times. Finally, he will jump up into the ceiling and strike you when he comes down. Keep running close to the walls, and he will run into them. Attack him when he recovers. Keep this up until he is defeated.