Defeating fastus
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.