The Legend of Zelda Phantom Hourglass Walkthrough part 6

Boss: Blaaz. Master of Fire.

Had to use the topscreen for this bossfight. When Blaaz splits into three smaller forms, look at the map to see how many horns they have. What you want to do is fuse them together using the boomerang. You must target them in a specific order though. You first need to target the one with one horn, then the one with two horns, and then three horns. When he's back to his original form just keep slashing him until he's dead.