Kronos

Aetheric God of and Chaos. He is known to help other antagonist called Zeus. Kronos is much more powerful than Zeus. If you speedrun the game (attempt complete the game very fast without leveling up) you cannot beat the boss, because you will instantly get killed by one of his special skills that deals brutal damage and would always get critical strikes that will kill you at one hit. It's health is also huge and if you find a special "Easter Egg" you can copy his skills and use them against him.