Antiform

Anti Form (アンチフォーム) also known as Anti-Sora, is Sora's Heartless from Kingdom Hearts II. It happens based on a hidden counter that increases as you use forms (but drastically decreases every time you use Final Form), and has no abilities. The form takes on the appearance of Anti-Sora from the first Kingdom Hearts game, only without the keyblade and with a dark mist rising from Sora's hands. Furthermore, unlike the Anti-Sora in Kingdom Hearts, his movements are somewhat feral in manner, as he runs about on all fours and attacks with his hands as though they are claws.

Most believe that this Drive Form exists due to Sora becoming a Heartless, specifically a Shadow. This is actually confirmed by Tetsuya Nomura in the Kingdom Hearts Ultimania guide. Since his movements in this Form are remniscent of that of Shadows and Neoshadows, this Drive Form is essentially the closest he ever gets to turning into a Heartless once more.

While Sora is extremely fast in this form, he can't attack with the Keyblade, instead he use his claws and feet, and can only revert when not in battle. It uses ALL of Sora's remaining Drive Gauge, and takes both party members. Note that if Sora consumes drive orbs while in this form, his Drive Gauge will decrease even further. It also makes Sora more vulnerable to damage, and his attack power drops, but his combo length is longer than most other combos in the game (Final Form can get in more hits at its higher levels, but it is very fast, and ends quicker than the Anti-Form combo). Anti-form cannot be levelled up, and has no specific abilities, but pressing Square will make him do a Dodge to Forward Lunge attack (Anti-glide). One more threat is that Sora can't use magic or items, meaning he can't be healed. Midair Doom deals Dark magic damage, but this doesn't count, due to it not being in the magic menu.

Many say that the way to trigger Anti-Form is by getting hit by Heartless while in other drives, such as Valor, Wisdom, or Master. However, this is wrong, and has been proven that the way to turn into Anti-Form is by repeatedly Driving into any but Final Form, racking up Anti-Points. Another theory is to turn into Wisdom or Valor form then when you next have full drive turn into the opposite OR master form, you will almost always turn into anti-form!

It is wise to not rack up anti-points before a boss battle because even though Sora deals lots of damage with Anti-Form's long combo's, he is also more vulnerable to damage and can't be healed.

Formula For Triggering Anti-Form

 * Fights in which Anti-Form never occurs: Pete (all fights), Barbossa (Port Royal), Hades, all battles involving outside characters (i.e. Mickey, Hercules, etc.)
 * Note: Once the scene where Sora battles Roxas (After you fight him in Final Mix+) has occurred, as long as the Two Across Keyblade, acquired from winning the battle and which bears the "Light and Dark" ability, is held, there is a 25% chance you will get Final Form instead. If you still get Anti-Form, it increases to 50%, and then 100%.

Representation
This form represents the darkness that sleeps within Sora's heart and his time of having been turned into a Shadow Heartless.

Trivia

 * Anti-Form looks very similar to Anti-Sora in the first game (Kingdom Hearts), only without a Keyblade.
 * While Anti-Form is normally impossible to activate manually, certain cheat devices can allow you to activate Anti-Form from the Drive Menu.
 * In Kingdom Hearts II: Final Mix+, During the fights against Vexen's Absent Silhouette and his data copy Vexen can make copies of Sora that are actually Sora in Anti-Form.
 * Despite showing almost no distinctive appearance apart from Sora's shadow, the Anti-Form's appearance does indeed changes in different worlds:
 * In Halloween Town the Vampire mask takes the form of a Shadow Heartless.
 * In Timeless River, the Anti-Form appears as a retro cartoon silhouette.
 * In Space Paranoids, the Anti-Form changes the armor completely black and the circuits to dark purple.
 * In Christmas Town, the Anti-Form changes Sora's Santa costume completely to black, a Heartless emblem can be seen on top of the hat though. (Applies only in Final Mix+)


 * Anti-Form is the only form that doesn't level up, and Sora doesn't get experience from enemies killed. It also takes all Sora's Drive Gauges, whether he has three, seven, or even nine.
 * Aside from Riku, Anti-Form is the only Player/Party member that may use dark-based magic attacks.


 * Anti-Form seems to be the counterpart of Final Form. Anti-Form is related to Darkness and Heartless and crouches down for many attacks while Final Form is related to Light and Nobodies and floats above the ground.
 * Although it has no Abilities, Anti does have a move where he shoots black fire-like arrows.
 * Though killing a boss with other forms will result in Sora being in the next cutscene in the mentioned form, being in Anti-Form will revert Sora back to his normal stage (with 0 Gauge)
 * Although the Anti-Form doesn't have a growth ability, if the player presses the square button while in this form, Sora will execute some kind of "Anti-Glide", in which he jumps backwards and dives forward a moment later.
 * Amazingly, when hacked to give anti form two keyblades, it is able to do tremendous damage, landing a midair combo has been seen to take 7 health bars off a Data Battle Boss in 7 seconds.
 * Possibly, Heartless see Nobodies as enemies, and the presence of a strong Nobody ( an Organization XIII member) is what increases the chance of Anti form coming out to fight during those battles.