No Heart

No Heart is a boss exclusive to Kingdom Hearts Birth by Sleep Final Mix. He is a data simulation of Xehanort in his Keyblade Armor, and is fought within the "Foresight unto Darkness" battle in the Mirage Arena. He wields Master Xehanort's Keyblade in battle. At the beginning of the battle, he sits on a throne in the Throne Room of the Land of Departure, and he later stands up to fight the character directly.

Design
No Heart wears a suit of Keyblade Armor branded with a single Nobody emblem centered on the torso, two protruding from his greaves, and two wrapping over his boots. His crown and shoulder pad are gold, while the rest of the armor is colored in light shades of blue and silver. He has two silver belts on his waist and what seem to be white feathers on his right shoulder in place of a spiked pauldron. Several cords crisscross in front of his torso, connecting a pair of baggy sleeves to massive, oblong pieces of armor worn on each arm. No Heart removes both of these sleeves and the straps before fighting. No Heart's faceplate is beak-like in structure and he wears clawed gauntlets. He also wears black pants underneath the armor. He wields Master Xehanort's Keyblade in battle. This Keyblade Armor is later worn by Xemnas in his Armored Controller form.

Like "Another", "No Heart" is an anagram of Xehanort without the X in the name.

First Phase

 * Summon Keyblades: Summons and hurls a multitude of keyblades at the player.
 * Corridor of darkness: Creates a corridor of darkness that pulls the player in. If the player gets caught in it, it will deal damage and immediately place the player above his floating keyblade (essentially completely open to his Summon Keyblades).

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: Transforms his keyblade into a set of gauntlets. A four-hit punching combo.
 * Three-four kick: Transforms his keyblade into a set of greaves. A six-hit kicking combo.
 * Upward slash: A single slash which knocks the player into the air.
 * Dash: Cloaks himself in darkness, and launches himself into a double dash.
 * Grab: Transforms his keyblade into a pincer, and grabs the player and hurls the upwards. You can escape this hold by repeatedly tapping.
 * Dark Firaga Burst: Fires several Dark Firagas from his fist.
 * Summon Keyblades: Summons and hurls a multitude of keyblades at the player.
 * Block + reversal: Holds his Keyblade up to block any oncoming attacks. If the player attacks him, he quickly uses Reversal to get behind and attack with either his Keyblade Combo or Three-Four Kick.
 * 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 blast: Transforms his keyblade into a sort of gun-mechanism. Fires three consecutive, light-purple blasts at the player.
 * Displace Keyblade: Transforms his keylade into the same mechanism as from the first-phase. The keyblade will constantly use Dark Firaga Burst and Summon Keyblades, while No Heart himself will attack the player 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.
 * Slow pool: Summons a pool of darkness in the ground. If the player touches it, they will be unable to move for a couple of seconds. You can marginally move by using your movement abilities.
 * Haste pillar: Summons a dark pillar of dark energy from the ground. If No Heart touches the pillar, his overall speed and speed of his attacks doubles. Touching the pillar yourself has no effects.
 * Keyblade Glider: Transforms his keyblade into a set of wings. This allows him to fly above the field (out of harm's way), and attack the player. In this state, he only uses the following four attacks: Dark Firaga Burst, Summon Keyblades, Shockwave, and Grand Explosion.
 * Shockwave: 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.
 * Grand explosion: 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, rivalled 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 a 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. The boss possesses an arsenal of potent dark-based attacks which can deal large, and possibly fatal damage. No Heart 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. The armor can also alter the shape of his Keyblade for strong attacks (a similar fighting style to the Lingering Will) such as turning it into 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, morphing it around his leg for powerful kicks, and turning it into a wing 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 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.

While there is no specific strategy for defeating No Heart, the basic method of winning is making sure the player is at a high level, over Level 80. The first phase of the battle can be won by using one or two Shotlocks on the Keyblade. As for the second phase, the player must be wary of No Heart's attacks. As stated above, Cure commands are absolutely essential. Most attack commands can be left out, since No Heart will most likely dodge after the first hit. Once More and Second Chance are to be equipped as well. Dodging is also necessary, although Terra is more vulnerable to damage than Ventus and Aqua due to his slower speed. A possible way of speeding the battle up is using Thunder Surge over and over again on No Heart in order to reach Rhythm Mixer's final attack, which can deplete quite a bit of No Heart's health if he is in range. Unlike Young Xehanort, victory against No Heart depends on careful timing instead of luck. Patience is also a virtue, since No Heart has more health than Young Xehanort and is harder to catch.

The reward for defeating No Heart is the Crown Unlimit Keyblade.

Trivia

 * The music that plays during No Heart's battle is Forze dell'Oscurita — Italian for "Forces of Darkness" — a remix of Forze del Male and Darkness of the Unknown, the battle themes of Ansem, Seeker of Darkness and Xemnas, respectively.