Chain Attack (XC3)

Chain Attacks are a battle mechanic in Xenoblade Chronicles 3. When the Chain Attack Gauge is full, a Chain Attack may be performed by pressing +. Chain Attacks allow for many s and other attacks to be performed in succession with higher damage and other bonuses without the enemy attacking. They are unlocked in Chapter 2 during the fight against the Gyanna Aspar.

Overview
When a Chain Attack is initiated, regular combat ceases temporarily; characters and enemies stop attacking and moving, though enemies will keep going through the motion of whatever art was in progress.

To begin the Chain Attack, three random are offered, any of which may be selected. The player may then attack using any Art (besides s) of a character of their choice, including the active Hero if there is one. When this happens, an amount of Tactical Points is added to a total for the current Chain Order. If the amount of TP added causes the total to reach or exceed 100, the Chain Order's effects are applied, and the Chain Order's matching character unleashes a powerful attack. If not, the player may choose an Art of a different character to attack with and increase the TP of the Chain Order. This continues either until the Arts cause the total TP to exceed 100, or the player runs out of characters to use Arts with; in the latter case, the Chain Attack ends.

When a Chain Order is initiated, the Chain Attack Gauge decreases by a third. If any Chain Attack Gauge remains at the end of a successfully-completed Chain Order, the Chain Attack continues and a new Chain Order may be selected. The Chain Attack may also continue if the conditions are met for getting an. Otherwise, the Chain Attack ends.

Once a character uses an Art in a Chain Attack, they become "inactive", and cannot be used again. Completing an Order "reactivates" a number of inactive characters, allowing them to be chosen again. If the previous Order was completed with 100-149 TP ("Cool"), only one character is reactivated; if it was completed with 150-199 TP ("Great"), two are reactivated; and if it was completed with 200 TP or more ("Amazing"), three are reactivated. (Certain circumstances, such as or specific, may allow for more characters to be reactivated.) Who is reactivated is chosen at random.

If a character is Incapacitated or suffering from Eclipse Soul when a Chain Attack initiates, they cannot participate; their particular Chain Order will not appear as an option, and they may not use Arts. With the exception of certain Hero Orders, characters cannot be revived from incapacitation during Chain Attacks.

Ending Chain Attacks
The following conditions will cause the Chain Attack to end: In all of the above situations, the Chain Attack Gauge fully depletes upon a Chain Attack ending.
 * The Chain Attack Gauge is fully depleted and no Ouroboros Order is available.
 * The player runs out of active characters to use Arts before 100 TP has been reached.
 * An Ouroboros Order is successfully completed.
 * The chain attack is ended manually when selecting a Chain Order.

Arts in Chain Attacks
When arts are used in Chain Attacks, they always gain their most beneficial effect, even if this would otherwise not be the case. Specifically:
 * If an art can be a Fusion Art, it always is, as if both the Class Art and Master Art are always ready.
 * If an art has a positional bonus effect, it is always triggered, no matter the actual position of the user and enemy.
 * If an art affects any allies in range, it affects all allies, no matter the actual position of the user and allies.

TP
The amount of TP gained by using an Art in a Chain Attack depends upon several factors. Every playable character and Hero has a certain amount of base TP; the first time they use an Art in a Chain Attack, this amount will always be added. A host of other conditions add to the amount of TP gained from using the Art.

If the character is reactivated and used in a subsequent Order, they will start with the total amount of TP given in the previous attack — the sum of their base TP and the extra TP gained from conditional benefits of using Arts in previous Orders. In this way, the amount of TP a character adds broadly increases over time in a Chain Attack.

The amount of base TP a character has can be increased with Accessories or Now That's Tactics!. The default amount is a reference to the extent to which the character fights tactically in-universe, with tactically-minded characters (e.g. Taion) having higher base TP.

Chain Orders
Chain Orders start with choosing an Order from among a selection of three random active characters. Each character's Chain Order is associated with a certain beneficial effect; this effect occurs if the Order is successfully completed by reaching 100 TP, and its effects typically last throughout the remainder of the Chain Attack. The strength of this effect typically increases every 20 s.

The currently active Hero may have their Chain Order appear in the selection. If chosen, the Chain Attack Gauge will not decrease, effectively allowing for a free round.

Ouroboros Orders
Ordinarily, Ouroboros forms do not appear in Chain Attacks. However, two situations may result in Ouroboros forms being used in the attack at the end of a Chain Order. This unlocked during the battle against Lambda Ferronis.

The first situation is if two characters in an Interlink pair ( and, and , or  and ) both have their associated Chain Orders completed in a single Chain Attack. In this case, one of the Chain Orders available in the following round will be an Ouroboros Order (randomly selected from the two characters in the Interlink pair in question), and (if the Order is completed) the attack at the end features both Ouroboros forms of the character in question. An Ouroboros Order may be available in this way even if no Chain Attack Gauge remains, effectively allowing for an extra round. However, the Chain Attack ends after such an Ouroboros Order, regardless of whether any Chain Attack Gauge remains or not.

The second situation is if the Chain Attack is initiated while the player controls an Ouroboros at Interlink level 3. In this case, only the Ouroboros Order of one of the characters in the Interlink pair in question will be selectable. If this Ouroboros Order is successfully completed, the Ouroboros Order of the other character in the Interlink pair will be the only Chain Order option in the next round. The Chain Attack ends after these two rounds.

In either case, if the Ouroboros Order is chosen, all characters are reactivated for that round, regardless of how much TP the previous round was ended with. Additionally, Ouroboros Orders will always satisfy the "Role Match TP" and "Force Match TP" bonus conditions.

Role effects
When an Art is used in a Chain Attack, the effect may be changed if the Art was used by an Attacker, Defender, or Healer.
 * First Blood: If an Attacker uses the first Art in any particular round, the amount of TP gained from their Art is multiplied by 1.25x.
 * Back in Action: If a Defender completes a Chain Order by causing the TP to reach 100 and the Chain Attack continues for another round, one of the reactivated characters will be that with the greatest TP. (The other reactivated characters, if there are any, are random as per usual.)
 * Point Limit: If a Healer's Art would cause the TP to reach/exceed 100, the TP will instead be set to 99, allowing for another character to use an Art in the round.

Heroes do not have these special effects. Instead, they each have their own unique effect when one of their Arts is used in a Chain Attack.

Damage multiplier
Chain Attacks have an extra damage multiplier which can be seen next to the Chain Attack Gauge. This multiplier increases whenever a Chain Order is successfully completed. The damage multiplier starts at 150% (125% on Hard difficulty) for regular Chain Attacks, and 300% (200% on Hard) for Interlink Lv. 3 Chain Attacks.

At the end of each round, a damage multiplier increase is calculated, starting at 100 percentage points (or 200 if an Ouroboros order was completed).

The chances of getting the best possible ratio gain can be increased if the Order's character forms a "key pair" with any of the characters used in the round. A key pair is formed with either the two characters of an Ouroboros pairing, or both a Hero and their class inheritor. Thus, the possible key pairs are:

The base increase then gets a special bonus as the player progresses through more rounds. This bonus is randomly calculated based on the table below. random(a, b) returns a random number between a and b, inclusive.

The round bonus is effectively capped at +50, so advancing further into the Chain Attack does not strictly increase the value, but it increases the chance to get the max value. (More specifically, the maximum becomes guaranteed starting from the third round.)

Then, the base increase also receives a boost depending on the round's result. It doesn't increase as rounds go on, but it has a higher cap for "Amazing" rounds. Furthermore, it doesn't depend on the exact number of TP gained during the round, but rather on meeting three thresholds.

If participated in the order, the increase is multiplied by 1.5x.

Finally, if the difficulty is set to Hard, the increase is halved. The increase is then added to the total damage multiplier, and a new round starts.

Additional gains
Some Heroes increase the damage ratio by a net amount when their order is completed. This occurs after the regular ratio gain described above. However, these gains are still affected by difficulty (i.e., they're halved in Hard difficulty).

Chain Attack gauge
A full Chain Attack gauge is worth 900 points. Once it is full, a Chain Attack can be started by pressing the Plus (+) button.

Several actions can fill or deplete the gauge. With the exception of 's completion bonus, the gauge can't be filled during a Chain Attack. Additionally, all gains are multiplied by 0.75x on Hard Difficulty, and 1.5x on Easy Difficulty. As an interesting quirk, this makes Fiona's completion bonus restore 450 points (50% of the full gauge) on Easy Difficulty, thus making it possible to get 2 extra rounds if less than half the gauge is left.

Additionally, the gauge can also be filled by performing Role Actions.

is the logarithm base  of , i.e.  (1.02, x) + (x / 3)

where

x = 1 + 100 * (Overkill Damage / Enemy Max HP)

Therefore, the more an enemy has, the more damage is needed during Overkill to get substantial rate gains.

Affected parameters
The Overkill bonus rate multiplies the following resources gained at the end of the battle:
 *  for all party members below level 99.
 *  for all party members equipped with a class that hasn't reached the maximum Rank.
 *  unlock progression for all party members.
 *  gained from enemies.
 * Enemy drop rate: that is, the chance for enemies to drop each of their items. This only works if the drop chance is not zero: for example, it won't make defeated s drop Gold Coins again (with the exception of es, who can still drop them after being defeated).