Black Jewel

"Ooh, free at last! I'm chock-full of power! I think I'll turn all this greedy sap's jewels into evil spirits! Bwah ha ha ha ha!!!"

- Black Jewel

The Black Jewel is the main antagonist in Wario World, and it serves as the game's final boss. Prior to the events of the game, Wario obliviously collected the evil Black Jewel, assuming it was simply another treasure, and it destroyed the newly-renovated Wario Castle once it awoke. Despite its name, it is actually purple (although its name may refer to its dark nature), and has one eye and several pink appendages somewhat resembling octopus arms.

Wario World
According to the game's intro movie, the jewel once granted wishes for people, feeding on their desires to grow power. It eventually grew so powerful, it became a huge threat to civilization, sending armies of evil spirits across the land in an attempt to conquer the world. The Spritelings were able to overpower and capture it somehow and seal it away in their ruins. One day, many years later, Wario found it and stole it, unbeknownst to the dreadful powers it held.

On the night that Wario is celebrating his huge gains in his newly-built castle, the jewel re-awakens, destroys the castle, turns most of Wario's treasures into monsters, and scatters the rest. Wario falls and lands in what has become of his castle; a strange hub-world with four main worlds attached to it, known as Treasure Square. Wario must complete these worlds and defeat their bosses in order to acquire the Huge Treasure Chest Key that will open the black jewel's Treasure Chest.

As a boss, the black jewel has three attacks. The first one is using its eye to fire a laser, creating a wall of fire. The black jewel will use this attack until Wario is trapped between two walls of fire narrow enough. If the space is very narrow, the black jewel will lower itself to the ground and fire shockwaves across the floor which will have to be jumped over, similar to those that Bowser makes in the final battle of Super Mario 64 and Super Mario Galaxy, except that these shockwaves are of each color of the rainbow. If the fire-walls are not very narrow, the black jewel will fire fireballs with limited homing capabilities out of its eye, which are easy to dodge if Wario is very close to the black jewel.

To defeat the black jewel, the player will have to free the five Spritelings that are trapped in crystals on the battlefield, which will smack themselves into the monster, knocking it unconscious. Wario must then pick it up and use any one of his attacks on it (one of Wario's Mad Moves must be used to damage it). The black jewel has eight HP, more than any other boss in the game. Once this HP has been depleted, the jewel, while leaking tears from both sides of its eye, will let out a piercing scream before exploding into pieces.

In the Japanese version, the black jewel has a second attack phase, where it has ten Spritelings in the first four health points, then it lowers to the floor and has several attacks: The black jewel also cracks up when it takes damage, and after four more hits it is defeated.
 * Pounding the ground to create a shockwave,
 * Creating a ring of fire,
 * Charging forward,
 * Spitting out a barrage of crates from its eye, which contain bombs or garlic.

Fortune Street
"The big treasure in this place is a wand, huh? Guess a silly stick is better than a Black Jewel!"

- Wario

The Black Jewel is mentioned by Wario on the Castle Trodain level of Fortune Street where Wario claims that a wand is a better treasure than a Black Jewel.