Eternal Session

Eternal Session is a limit that appears in Kingdom Hearts II. Together, Sora and Riku can use the joint attack, Session.

Mechanics
In Kingdom Hearts II, Eternal Session is an action ability exclusive to Riku. It costs 3 to equip and all of Sora's MP to use. Its Limit Gauge has a duration of 5.1 seconds. The limit begins with Session (セッション), in which Sora and Riku perform a rapid flurry of attacks. Then, Last Saber (ラストセイバー) becomes available in the Attack slot, in which Sora and Riku rapidly stab an enemy with their Keyblades, and Dark Cannon (ダークカノン) can be used as a Reaction Command, allowing the duo to fire a barrage of dark orbs at enemies. Afterwards, Sora and Riku turn their backs toward each other, and the next phase of the Limit begins. Overriding the Attack command, XIII Blades (XIIIソード) has the duo summoning thirteen swords to perform a spinning slash attack. After using Last Saber or Dark Cannon twice, the next technique, Master Hearts (マスターハーツ), is used automatically and involves Sora and Riku coating their Keyblades in an aura and slashing opponents together. After XIII Blades or Master Hearts is used twice, All's End (オールオーバー), can be used, in which Sora and Riku's Keyblades float side-by-side in energy orbs that reel in enemies before exploding. During the limit, Sora can move around freely. The limit can be cancelled early through the Stop (やめる) command in the Limit slot.

Kingdom Hearts II

 * Riku has Eternal Session as a default ability.

Kingdom Hearts 3D: Dream Drop Distance
During the game's opening FMV, Sora and Riku are seen using the Master Hearts portion of Eternal Session against Xemnas.