Experience Boost

Experience Boost (EXPチャンス), also translated as EXP Chance and EXP Boost, is an ability introduced in Kingdom Hearts II. It doubles the experience the user earns for defeating enemies when at low HP.

Mechanics
In Kingdom Hearts II, Experience Boost is a that costs 3  to equip, 4 AP in Kingdom Hearts II Final Mix. It doubles experience earned when below 50% of max HP.

In Kingdom Hearts Birth by Sleep, EXP Chance is a that can be equipped once. It doubles experience earned when below 25% of max HP.

In Kingdom Hearts 3D: Dream Drop Distance, EXP Boost is a that can be equipped once. It doubles experience earned when below 25% of max HP.

Strategy
Experience Boost can be difficult to keep active while farming EXP, as it requires Sora's health to be at risk, but it can also be inadvertently deactivated if Sora picks up HP Prizes from defeated enemies. In order to maintain Sora's HP in the critical range without dying, the player should equip Second Chance, Once More, Damage Control,, apply any available Defense Boosts, and unequip Jackpot, Draw, and Lucky Lucky.

Experience Boost is especially hard to utilize at the beginning and at higher difficulties. A way to utilize it is to beat enemies one by one and then run to a different checkpoint, then back. This way if Sora is killed, the player can retain all the experience gained until that point. This is especially good for critical mode as when Sora has less than half of his total HP at the beginning of the game, most enemies can kill him with one hit. The best way to grind to level 99 is to kill the Nobodies from the first save point in The World That Never Was all the way to The Door to Darkness as the player will level to 99 very quickly. This may be tricky at first, but it gets easier as Sora levels.

Kingdom Hearts II

 * Sora learns Experience Boost at levels 7 with the Dream Rod, 9 with the Dream Sword, and 17 with the Dream Shield.
 * The Gull Wing has Experience Boost as its Equipment Ability.

Kingdom Hearts Birth by Sleep

 * EXP Chance can be attached to a or  Command recipe through Command Melding, either randomly or by applying a Abounding Crystal.

Kingdom Hearts 3D: Dream Drop Distance

 * Sora and Riku can purchase EXP Boost from the Cera Terror Ability Link for 300 Link Points.
 * Sora and Riku can purchase EXP Boost from the Drill Sye Ability Link for 300 Link Points.
 * Sora and Riku can purchase EXP Boost from the Keeba Tiger Ability Link for 300 Link Points.