The Sea Serpent is a boss from Hero of Sparta 2. It appears twice during the game and is also seen in the opening cutscene.
Battle[]
The first time you fight the sea serpent, it automatically starts off with a focused kill. If you fail the sequence, you will die instantly. The second fight however, you must fight like you would with a normal enemy. Then, when the focused kill icon pops up, you will do the exact same button sequence as you did with the first battle with the monster.