Demaseor
From Lunar Shadow Project Wiki
Demaseor is a large blue genderless monster appearing in Solar Shadow 2. It is the boss of the Sky Platform. Defeating it is required for endings 1, 2, 7, and 11. It is said to be the spawn of Grialdyn.
In-game
Demaseor has 500 HP, the most of any boss. It attacks using wind, which is not directly lethal but can knock Selena off platforms, as well as magic beams.