Reaction Command

Reaction Command is a feature introduced in Kingdom Hearts II. At certain points in the game, a reaction command can become available to the player, and these are to be executed by pressing the triangle button. Doing so often offers great benefits to the player, and sometimes are the key to continuing in the game.

There are dozens to perform, and only a few are listed. (Please add more.)

=Non-Battle Reaction Commands=

Talk
Used to talk to NPCs.

Open
Sora or Roxas uses the Keyblade to open chests.

=In-battle Reaction Commands=

Reversal

 * Sora (or Roxas) quickly slides around an enemy, confusing and paralyzing all Dusks in the immediate area for a short time.
 * Used against: Twilight Thorn's lightning, Xemnas's lightning, and Dusks

Show Stealer

 * Sora jumps behind Demyx's back and hold his Keyblade in a guitar fashion. A light tune is then heard and Sora smacks Demyx into the air.

Rob Scythe

 * Sora evades Marluxia's slash and pulls up his scythe with the Keyblade, after gaining control, Sora throws the scythe towards Marluxia, damaging him and earning back his count down numerals.

Learn

 * Sora snatches an attack from either Xaldin or a Dragoon, leaps into the air, thrashes downward, Keyblade first, and lands on the enemy. The charging phase (Stealing the attack) can be done up to nine times if the normal attack is not used.  Magic can still be used freely.
 * Used against: Xaldin or Dragoon Nobody.

Wild Dance

 * Sora grabs a Water Form and swings it around his head, attacking the other water forms in the area.
 * Used against: Demyx's Water Forms

Warp Snipe

 * Sora jumps in front of a crossbow bolt and deflects it.
 * Used against: Xigbar or Sniper Nobody

Fail-Safe

 * Sora grabs an Assassin that is about to self-destruct, and throws it towards the ground, dealing damage to nearby enemies and forcing other Assassins to emerge from the ground.
 * Used against: Assassin Nobodies

Berserk

 * Sora grabs his opponent's weapon and floats around, picking up additional non-boss enemies.
 * Used against: Saïx or Berserker Nobody.

Eclipse

 * Sora, holding a Berserker or Saïx's claymore, flips backwards and hits the enemy. The combo can be continued for two more attacks.  Each attack deals half the normal attack damage.
 * Used against: Saïx or Berserker Nobody, when holding their claymore.

Magna Storm

 * Sora, after three successive Eclipse attacks, throws all his strength at the enemy, dealing triple damage with each strike.
 * Used against: Saïx or Berserker Nobody.

Overtaker

 * Roxas leaps at Axel, repeatedly attacking him with both keyblades.
 * Used against: Axel (in the basement of the Simulated Twilight Town)

Clear Light

 * Roxas throws Axel to the ground, forcing him to turn the lava-flooded floor back to normal.
 * Used against: Axel (in the basement of the Simulated Twilight Town)

Burst Edge

 * Roxas throws both his Keyblades at Axel, forcing him out of the wall of flame.
 * Used against: Axel (in the basement of the Simulated Twilight Town)

Key Counter

 * When the Twilight Thorn tries to punch him, Roxas jumps over the Twilight Thorn's hand, and slashes its face.
 * Used against: Twilight Thorn

Lunarsault

 * After being thrown into the air by the Twilight Thorn, Roxas slashes it in the head while coming down.
 * Used against: Twilight Thorn

Break Raid

 * After tipping Roxas off the pillar, the Twilight Thorn creates a giant orb. Roxas throws the Keyblade into the orb, causing it to explode.
 * Used against: Twilight Thorn

Facedown
Sora forcefully breaks the curse Xemnas laid on him, then rushes up the side of the tower while Xemnas jumps down from the top. (The next action command is determined by how far apart Sora and Xemnas are when the player activates it.)

Clash
Sora and Xemnas pass by each other without attacking.

Break Through
Sora strikes Xemnas, doing minor damage.

Finish
When in close contact with Xemnas, Sora blocks and counters Xemnas' attack, slamming him into the tower.(In Final Mix+, successfully activating this reaction command will leave Xemnas with 1HP.)

Slicer
When facing a rising block from the skyscrapers, Sora does a slight jump back while twirling and charging his Keyblade. He then lunges through the block and executes three flashing slashes, slicing the block apart.

Skyscraper
Sora slices the blocks from skyscrapers while jumping from the sliced blocks to approach the Castle.

Stunt Dodge
Sora makes a high leap and jumps to the other side of the cannon. A Reaction Command used to escape the attacks of the cannon.

Riding Shot

 * Sora locks on one of the skyscraper blocks and bats it towards the Nobody Dragon.

Meteor Rain

 * Riku executes a 360 slash that breaks the skyscraper block, launching the debris towards the Nobody Dragon, breaking it's wing shield.

Break Free

 * Riku leaps and dispatches Xemnas' grip on Sora, forcefully negating Xemnas' force attraction with his own strength.

Block

 * Riku spins his Keyblade and blocks the rapid Aerial Blades fired by Xemnas. Block also replaces Sora's attack command, since it is crucial to press the buttons(both reaction command and attack buttons) in order to survive the inundation of Aerial Blades.

Rising Sun

 * After Sora attacks an Armored Knight, he dives down to punch the enemy up to 5 times.
 * Used against: Armored Knight (after attacking it)

Firagun and Blizzagun

 * Sora either stabs his Keyblade into the Volcanic Lord or grabs the nose of the Blizzard Lord, and throws him into the remaining one
 * Used against: Blizzard and Volcanic Lords

Snag

 * Sora jumps up and grabs a Surveillance Robot from behind.

Sparkle Ray

 * Sora spins in a circle as the Surveillance Robot fires its laser, effectively destroying or severely injuring all surrounding enemies.

Bat Cry

 * Sora latches the Keyblade onto one Hook Bat's hook. Sora then spins through midair, hitting airborne enemies with the captured Hook Bat.

Flash Block
Sora blocks all Sephiroth's rapid sword slices in one go (*only applies in one of Sephiroth's combos.)