King's Curse is a boss in Dark Cloud. It is found on floor 18 of the Sun & Moon Temple. The King's Curse is the spirit of an ancient king that has been corrupted by the Dark Genie. It stands watch over the door to the Moon Ship.
Ungaga's charge attack will disperse the black cloud surrounding the boss, leaving him open for attack. The black cloud will reform after a couple of seconds. Repeat the process of dispersing the black cloud around the boss using Ungaga's charge attack, then attack the King's Curse (using any character from the party), until it is defeated.