Hyness is the main villian for the majority of the story in Kirby Star Allies. He's a priest of dark magic with plans to unleash doom upon Kirby's world and the surrounding planets.
A master of powerful magic, you shouldn't take Hyness lightly.
Eventually you see that Hyness is rather ugly. But he eventually summons dark versions of his mage minions to fight you. Overall I thought the fight was easy enough to defeat.
But then Hyness uses the last of his energy to summon his lord Void Termina. You had one job Kirby!