No Heart

No Heart is a simulated version of Xehanort wearing Keyblade Armor. It is an optional boss in Kingdom Hearts Birth by Sleep Final Mix that serves as the only enemy in the "Peering into Darkness" battle at the Mirage Arena.

Kingdom Hearts Birth by Sleep Final Mix
No Heart is an opponent in the Mirage Arena. Terra, Ventus, and Aqua confront No Heart separately, and ultimately triumph in the process.

Design
No Heart wears a suit of Keyblade Armor. The Keyblade Armor itself is adorned with several Nobody emblems; one appears on the piece of armor covering No Heart's torso, two protrude from No Heart's greaves, and two more cover the boss's boots. No Heart's crown and shoulder pad are gold, while the rest of its Keyblade Armor is platinum blue and silver in coloration. No Heart wears two silver belts on its waist; instead of a spiked pauldron, white feathers cover its right shoulder. Several cords crisscross in front of No Heart's torso; these connect a pair of baggy sleeves to the massive, oblong pieces of armor No Heart wears on each arm. Before fighting, No Heart removes both of these sleeves, as well as the straps connected to them.

No Heart's faceplate is beak-like in structure; the boss wears clawed gauntlets, and black pants appear underneath its Keyblade Armor. No Name is No Heart's weapon of choice; the boss's Keyblade Armor shares its design with the armor worn by Xemnas in his Armored Controller form as well as Xehanort's actual Keyblade Armor from his time training under Master Odin.

"No Heart" is an anagram of "Xehanort" with the "X" removed.

Attacks

 * First Phase
 * Keyblade shot: Summons and hurls a multitude of Keyblades at the player character.
 * Corridor of darkness: Creates a corridor of darkness that pulls the player character in. If the player character gets caught in it, it will deal damage and immediately place the player character above his floating Keyblade, completely vulnerable to his Keyblade Shot.
 * Dark volley: Fires a stream of dark projectiles at the player.
 * Second Phase
 * Keyblade combo: A quick four-hit combo.
 * Kick wave: A wide swipe that releases a wave of energy. It is used as a followup to his other combos.
 * One-two punch: Formchanges his Keyblade into a set of gauntlets. A four-hit punching combo.
 * Dark kick: Formchange his Keyblade into a set of greaves. A six-hit kicking combo.
 * Upward slash: A single slash which knocks the player character into the air.
 * Keyblade slash : Summons an array of Keyblades that swarm the player character in mid-air.
 * Sonic impact: Cloaks himself in darkness, and launches himself into a double dash.
 * Grab: Formchanges his Keyblade into a pincer, grabs the player character, and hurls them upwards. The player character can escape this hold by repeatedly tapping.
 * Dark volley: Fires several Dark Projectiles from his fist.
 * Keyblade shot: Summons and hurls a multitude of Keyblades at the player character.
 * Block & reversal: Holds his Keyblade up to block any oncoming attacks. If the player character attacks him, he quickly uses Reversal to get behind and attack with either his Keyblade Combo or Dark Kick. This move is quicker in the HD 2.5 Remix.
 * Explosive punch: A somewhat more rare finishing attack, which he uses as a follow-up to his One-Two Punch. He creates a large dark blast from his fist.
 * Triple shot: Formchanges his Keyblade into a sort of gun-mechanism. Fires three consecutive, light-purple blasts at the player character.
 * Shield slow: Formchanges his Keyblade into the same mechanism as from the first-phase. The Keyblade will constantly use Dark Firaga Burst and Keyblade Shot, while No Heart himself will attack the player character with his hand-to-hand combos. The Keyblade can be destroyed, but after about anywhere from 5 to 15 seconds, he will return it to its original state.
 * Distortion of space and time: Summons a pool of darkness or dark pillar of energy in the ground. If the player character touches it, they will be unable to move for a couple of seconds or doubles their speed and power. If the result is that of a Slowing affect the player character can make slight movements by using the movement abilities. If that result is that of a Haste effect, the player character's movement speed increases, increasing the distance taken per step.
 * Keyblade glider: Formchanges his Keyblade into a set of wings. This allows him to fly above the field (out of harm's way), and attack the player character. In this state, he only uses the following four attacks: Dark Volley, Keyblade Shot, Charge Crash, and Big Bang.
 * Charge crash: Slams down on the ground from the air, creating a large shockwave. Can easily by avoided by jumping. He only uses this during Keyblade Glider.
 * Big bang: He hovers in midair, and concentrates dark energy then creates an enormous explosion. If you are hit by the last, your HP will automatically be reduced to 1 (provided you have Second Chance equipped), your Focus and Command gauges completely drained, and all of your deck commands will automatically enter their cooldown periods, with the exception of Items. The only way to avoid this attack is to run to the very very edge of the area, or withstand the damage and utilize an Elixir after the hit.

Strategy
No Heart is one of the strongest secret bosses in the game, rivaled only by Young Xehanort. His attacks are strong and can deal heavy damage. In terms of preparation, the character should be at a high level, have a strong Keyblade, max HP, and lots of Cure and Potion commands, as well as have the Second Chance and Once More abilities equipped.

In the first phase of the battle, No Heart remains stationary, protected by a large barrier of dark energy. To disable the barrier, the character must attack No Heart's Keyblade, which is constantly floating around. In terms of offense, No Heart will summon a swarm of flying Keyblades from the Keyblade Graveyard that can be blocked, or even destroyed by commands such as Raging Storm, to attack the character and sometimes use an advanced Corridor of Darkness that absorbs and traps characters on the barrier ( must be pressed repeatedly to break free), and may use Dark Volley. No Heart's Keyblade is vulnerable to any attack. After dispelling the barrier, the fight becomes more serious as No Heart rises from the throne, removes his cape and challenges the character directly.

This is the harder phase of the battle. No Heart possesses an arsenal of potent dark-based attacks which can deal large, and possibly fatal damage. He mainly uses Sonic Impact, darting around the arena to attack the character. The boss can utilize Dark Volley to strike from a distance, as well as summon flying Keyblades to attack. The boss can create waves of dark energy by swinging his Keyblade. He may also leap into the air and slam the ground to create a large shockwave. No Heart can use Reversal to maneuver around the character to unleash more Keyblade strikes, and may completely block attacks with his Keyblade. No Heart also can create large pools of dark energy that will either slow down or speed up anything that is inside, and may even bind the characters in place with no means to move aside. He can also Formchange his Keyblade into a myriad of weapons, like a claw to grab characters ( must be pressed repeatedly to break his grip), a spinning duel edge blade, a gun that can shoot powerful shots, greaves for powerful kicks, and a Keyblade Glider to fly. From the air, he will either shoot more dark energy blasts, summon more flying Keyblades to attack, dive at the hero repeatedly, or use his most powerful attack: A large explosion of dark energy that will instantly drain all HP, Commands, the Focus Gauge, and may leave the player character stunned if characters are in the vicinity. He may also telekinetically command his Keyblade to attack characters directly and to absorb any damage directed to him.

Heal Strike, Renewal Block or Barrier, and a Command Deck containing Thunder Surges alternating with Cure spells will lead to an easy victory. Once More and Second Chance should be equipped as well. Thunder Surge is particularly useful compared to other techniques because it can lead into the powerful Rhythm Mixer Command Style. Victory against No Heart depends on careful timing and conscientious healing.

In the Kingdom Hearts HD 2.5 ReMIX version, like with Young Xehanort, the difficulty of No Heart's battle appears to have been toned down. While he is still as dangerous as in the original version due to his increased evasion and speed in the HD Remix, he is now vulnerable to Shotlock attacks like Aqua's Lightbloom, which take away a good portion of his health.

The reward for defeating No Heart is the Royal Radiance Keyblade.