The fourth boss you beat would be Elric SeaGem, a wizard student being controlled by a seamonster named Seth OceanWinds. After you beat Elric, whom is rank 8, you then defeat Seth, whom is rank 10.
Seth: He's a purple seamonster, covered in seaweed. Meaning that you can barely see his skin, but slightly. His eyes are yellow and glow each time he uses a spell. He holds a large purple an yellow staff. The top part is a sphere that's dark purple and it glows slightly. The rest of the staff is light purple and yellow, it's divided to in sides vertically. The top is light purple and the bottom is yellow. He has a large shark-like tail coming from the seaweed. Seth has fins that stretch out of the seaweed, as well.
I think there should be a boss thats a crab and he has armor that has sea weed and a big staff that has sea weed on it. He should be a big strong crab he should be ice and he should be a rank 9 his life should be 4000. His armor should be black and white and his staff should be gray. He should have a helmut thats like the greek soldiers would wear. It should be black and the top part that sticks out should be white. :D Please put this boss in celestia thanks