Scarecrow is a master of fear, and can create a chemical to heighten it. Actually, in this battle, he has very few attacks. You start off in a gas-filled room. You will see ghost-like things flying around. ONe hit will kill them. Look at the blue gas surrounding the room. Notice that the gas seems to part in some areas, and you can hear footsteps. Run around, rolling where the gas clears. If you are lucky, Scarecrow (who was invisible), will appear. Then, beat him up and repeat.

Scarecrow is fairly easy, because he rarely attacks. To start off, look down at the floor. It is covered with some sort of blue gas. The trick to defeating him is as follows. First, avoid or destroy all of the ghosts flying around. Notice how the gas seems to part in certain areas (byt not your own). This is Scarecrow walking. Roll into him. He is invisible, and this lets you see and beat him up. After awhile, he turns invisible again. Repeat the steps until he is defeated.