Dark Hide

The unnamed Heartless is a Pureblood Heartless that appears in Kingdom Hearts Birth by Sleep Final Mix. It is fought by Aqua in the Realm of Darkness in the game's Secret Episode

Design
The unnamed Heartless is a massive creature that resembles the Dark Thorn. It has a dark purple and black body with dark magenta spikes running down its back, as well as a "mane" of dark magenta tentacles around its head. Its tail has a dark magenta tip, and the Heartless sports four purple claws on each of its four legs. The most distinctive feature of the unnamed Heartless is its yellow eyes, which occasionally glow red. The Heartless also sports a jagged mouth, blue markings on its face and body, and chains around its forelegs. Its body is rather long and thin and, despite its massive size, the Heartless moves quite quickly.

The Heartless is able to cloak itself in darkness, obscuring all of its features, save for its eyes, which glow bright red. The Heartless seems to be able to use its eyes to zoom in on the objects it looks at; from its perspective, everything has a very faint red tint. Glowing red veins are present around the sides of the unnamed Heartless's field of vision. The Heartless frequently creates disorienting after-images of itself as it moves, including red, green, and purple versions of itself.

Kingdom Hearts Birth by Sleep
While making her way through the Valley of the Darkness in an attempt to return home, Aqua is stalked by the unnamed Heartless. Aqua detects the Heartless's presence, and the Master Keeper appears in her hand. The unnamed Heartless attacks Aqua from behind, knocking her down, but the young Keyblade Master quickly retaliates with a Fire spell. This forces the unnamed Heartless to flee back into the shadows; Aqua can only see its glowing red eyes.

Aqua realizes that her attacker is not an Unversed, and like the creatures she has faced in the Realm of Darkness thus far, it is one of the realm's denizens. Aqua engages the unnamed Heartless in battle, emerging victorious after a strenuous showdown.

Strategy

 * Attacks
 * Claw Swipes: The unnamed Heartless swipes Aqua quickly with its claws.
 * Tail Whip: The unnamed Heartless spins around, hitting Aqua with its tail.
 * Buzz Saw: The unnamed Heartless performs a damaging midair flip.
 * Fire Charge: The unnamed Heartless emerges from the shadows and charges at Aqua, leaving a trail of flames in its wake.
 * Shadow Bomb: The unnamed Heartless shoots orbs of dark energy which, after a few seconds, expand into damaging forcefields.
 * Mega Flare: The unnamed Heartless shoots a large fireball at Aqua.
 * Illusion Spin: The unnamed Heartless spins at high speeds around the outskirts of the battlefield, using four of its after-images to charge at Aqua, before pouncing from above and into the center of the area, creating a damaging shockwave.
 * Illusion Slash: Each of the unnamed Heartless's after-images attack Aqua with their claws.

The unnamed Heartless is a fast, fierce, and unpredictable opponent. In the first phase of the battle, the Heartless attacks from within the darkness, visible only by its glowing red eyes. The boss will attempt to charge at Aqua, and when it does the battle shifts to its point of view, making it hard to dodge. The Heartless also attacks with savage claw swipes and tail spins. The best way to deal damage to the Heartless in this phase of the fight is to patiently wait until just after the scene where it looks at you through its point of view, then quickly use Barrier to block the incoming attack and finally to use Aqua's counter attack to deal damage. The Heartless will then just stand there idly for a few seconds before returning to the sanctity of the shadows, so be sure to get as many Keyblade strikes in as you can. If you have Teleport equipped sometimes Aqua will teleport behind the Heartless instead of blocking its attack with Barrier. However, this does leave the Heartless vulnerable as all of its attacks in this phase are focused on what's in front of him. After dealing around one and a half health bars of damage to the Heartless, it will reveal its true form, starting the next phase of the fight.

The second stage of the battle is the same as the first, with the exception of the new attacks in the boss's arsenal. The boss still retains its claw swipes and spin attacks, but can now charge at Aqua, leaving a trail of flames in its wake. Also, the Heartless's movements become more erratic, making it hard to land hits. However, the Rhythm Mixer Command Style finisher deals great damage to the boss. After another round of combat, the Heartless unveils the rest of its attacks.

In the final round of the fight, the Heartless now uses red, blue, and green afterimages of itself for offensive and defensive purposes. It may spin around Aqua, its afterimages charging at her while it slams the ground, creating a shockwave. The boss can also shoot dark energy orbs that, after a few seconds, expand, damaging Aqua if she steps to close. It also utilizes a variant of the Mega Flare command, wherein it shoots a large fireball at Aqua. With some patience, Cure and potion commands, and high HP, the Heartless will eventually fall.