Regen

Regen is an ability found in Kingdom Hearts: Chain of Memories, Kingdom Hearts Birth by Sleep, and Kingdom Hearts Re:coded. It automatically restores the player's HP a little at a time.

Mechanics
In Kingdom Hearts: Chain of Memories and Kingdom Hearts: Re:Chain of Memories, after the Oogie Boogie enemy card is activated, it restores health ten times before the effect runs out. When Sora's HP is in the alarm zone, Regen causes him to regain health more quickly.

In Kingdom Hearts Re:coded, Regen restores Data-Sora's HP every few seconds while active.

Kingdom Hearts: Chain of Memories

 * The Oogie Boogie card has Regen as its effect.

Kingdom Hearts Birth by Sleep

 * The Cinderella Dimension Link has Regen as its level 2 ability.

Kingdom Hearts Re:coded

 * The Lady Luck ⑤ has Regen as one of its level 3 Clock Abilities.
 * The Oathkeeper and its upgrades have Regen as one of their level 2 Clock Abilities.
 * The Lionheart 3° and its upgrades have Regen as one of their level 3 Clock Abilities.
 * The Ultima Weapon 〉 and its upgrades have Regen as one of their level 3 Clock Abilities.

Other appearances
In Kingdom Hearts 358/2 Days, Cura has the same effect as Regen.