Overdrive (オーバーライズ) is an ability introduced in Trails of Cold Steel II. A small, red icon at the upper right corner of the screen gradually fills as actions are performed in battle. Once filled, two linked characters can go into Overdrive for three uninterrupted turns, which restores 30% of HP, EP, and CP, clears all status abnormalities, causes all attacks to unbalance enemies, and allows all orbal arts to be cast instantly (including Lost Arts).
Rean can always Overdrive with any other party member.
Other members of Class VII may Overdrive with each other after completing the blue Trial Chests found during the game. A typical Trial Chest contains a boss battle to challenge two specific characters, unlocking Overdrive for that pair. They must be both present in the party (attack or support) and they will be the only participants when the chest is opened. Some Trial Chests require four characters and unlock Overdrive between each of the six combinations.
Guest party members may only overdrive with Rean and certain Class VII members whom they have a special connection with (Toval with Sara, Claire with Millium, Sharon with Alisa).
In the Reverie Corridor in Epilogue: "Winter's End", all restrictions on Overdrive pairings are waived.
A second red icon is unlocked starting in Act 2: "The Awakening Lions", day 1, and allows storing up to two Overdrive actions at one time.
When a pair of characters reach link level of 7, the common link ability Overdrive 2 increases both characters' damage output by ×1.2 during Overdrive.
Crafts such as Rean Schwarzer's Spirit Unification and Lloyd Bannings's Burning Heart 2 which have 0 delay do not count toward the uninterrupted turns if not used as the final turn. This allows them to apply the self buff then immediately act with Overdrive still in effect.
All victories with Overdrive in effect count as though a link attack is used for victory dialogue, even if the final attack was an orbal art with no link attack.
Switching a character's link partner or calling in a support character will cancel the Overdrive.
Overdrive is a more fleshed out interpretation of the Burst system introduced in Ao no Kiseki.