Vision

Visions are a major gameplay mechanic and story point in Xenoblade Chronicles. As he wields the Monado, Shulk occasionally gets glimpses of what will happen in the future, which he can use to his advantage.

As a battle mechanic
After a certain point in the story, the player unlocks the ability to see visions in battle. Visions occur if an enemy is about to use an art that would leave its aggro target with 15% HP or less. If this is the case, the player will see a vision of the attack landing, before being returned to the battle proper with information displayed on what the forseen attack will do. This information is presented in the form of five "tags".
 * 1) The enemy tag shows which enemy is using the art. For most foes it is a generic image; certain enemy types and many bosses have a unique one.
 * 2) The art tag shows the name of the art, coloured to indicate what it is: a physical art (red text), an ether art (blue/purple text), or a talent art (white text and a level number). Talent arts can also be physical or ether, but this is not distinguished. If the art has an area of effect, an appropriate icon will be displayed: a line, a cone, or a circle (there is no differentiation between "circle around user" and "circle around target").
 * 3) The target tag shows the party member who is the focus of the enemy's aggro, and thus the main target of the art.
 * 4) The damage/status tag shows how much damage the art will do, as well as one of the statuses it will inflict (if any). If the damage is lethal, a skull is displayed.
 * 5) The timer tag shows how much time is left (both in rounded-up seconds and as a bar) before the forseen attack is used. The timer starts at 8 seconds, or 12 if the art is a talent art.

When a vision is active, the player's actions can change what will happen. Changing a vision will break the relevant tag, replacing it with an updated one that reflects the new future, and change the music to Visions of the Future for the rest of the battle. Ideally, the player changes the future to one that is better than the one that triggered the vision. While some of the tutorials imply that there is only one right way to deal with each type of vision, this is not necessarily the case. Breaking a tag generally also breaks all other tags below it, as they depend on it. The following actions may break tags and change the future:
 * The timer tag breaks if the foe is d. The timer will pause until the topple ends. This can grant more time to set up a better defence against the vision, but it may also cause an established defence to expire before the new countdown completes.
 * The damage/status tag breaks if the amount of damage or the status inflicted change. Debuffing the foe's offenses, buffing the target's defences, defending against debuffs, or helping the target out of being toppled or dazed may all have an effect. The damage tag also breaks if the attack's lethality changes, for example if the target is healed enough that they will now survive the hit.
 * The target tag breaks if the enemy's aggro target changes. It is possible for two party members to trade aggro back and forth, causing the target tag to break many times. It is advisable to try and avoid changing aggro if the current target is well-suited to take the incoming attack.
 * The art tag breaks if the enemy is d, put to, confused, or placed under Arts Seal. In addition, the rest of the vision is blanked until the status ends. Once the status does end, a new vision will occur in which the enemy uses a different art, even if the results would normally be too weak to trigger a vision. This also means the enemy may use an art that it would not normally use in this situation.
 * The enemy tag breaks if the foe is killed, and the vision never takes place.

Breaking tags also raises the of all party members. It is possible to manipulate some effects to break many tags in quick succession for a large tension boost. However, breaking most tags will only raise tension within the current level, and cannot move it to the next level.
 * Timer tag: +20
 * Damage/status tag: +25
 * Target tag: +50
 * Art tag: +100
 * Enemy tag: Set to very high tension

If there is one block of available, the player may spend it to "warn" either (or both) of the other two party members. Warning a party member grants them full talent gauge and allows the player to select an art for them to use, regardless of cooldown. They will then use the selected art against the enemy causing the vision. Each party member can only be warned once per vision.

While an enemy is the subject of a vision, they remain in their "windup" state and cannot move or auto-attack. During this time, it will take +50% damage from ether attacks if it is using a physical art, and +50% damage from physical attacks if it is using an ether art. The lack of auto-attacks means the party can act a bit more freely without worrying about background damage.

Other notes about visions include:
 * Shulk does not have to be in the party for any of the vision system to operate.
 * Auto-attacks cannot trigger visions.
 * Visions only trigger based on the HP of the aggro target. Anyone else who happens to be in the area of effect may get whalloped without warning.
 * Visions only trigger based on how much HP the target will be left with after the raw damage. Any damage done via debuffs is not counted.
 * Only one vision can be active at a time. If another enemy does something that would trigger one, it just happens, which will probably be a big problem.
 * Certain arts are set to always trigger a vision, even if they would deal low damage (or even miss entirely).
 * Warning will empty her talent gauge rather than filling it.
 * If the target of a vision is out of the art's range when the timer expires, the attack will miss.
 * If the target of a vision has an gem equipped, it is possible to get a vision where they take damage equal to or greater than their remaining health, but is not marked as lethal. This reveals that the Unbeatable gem will trigger on the attack.
 * Enemies with a Soul Read aura active can change their visions after the timer runs out, messing up the player's attempt to change the future to their liking.
 * In the original version, warning a party member will instantly cancel their current action so they can use the selected art as soon as possible. In the Definitive Edition, they must instead wait for their current action to complete before the warning's art can be executed.

In Xenoblade Chronicles 2
Visions appear in Xenoblade Chronicles 2 if is equipped as a Blade of an active party member.

As an inventory convenience
When the player obtains certain items for the first time, they may receive a vision. In this vision, a party member stands alongside either a collectable orb or a chest and states that they just found the last of the item necessary for some future purpose. The item is then marked in the player's inventory with a white "!", indicating that this item will be useful in a future quest, and thus it should probably be kept rather than sold, traded, or gifted.

As a plot element
Once he starts to use the Monado, Shulk begins receiving visions of the future. Without much warning, he sees a bright flash followed by a short glimpse of what will happen. Visions are usually of an injury or death, and Shulk slowly realizes that he can act to change them to avert the tragedy. Some of Shulk's visions occur days or weeks in advance, or may be triggered by nearing or touching a related object, and may repeat as the depicted future approaches.

It is later revealed that Shulk is not the only person to have visions. Alvis, the seer of Alcamoth, has his own way of receiving visions: he performs a ritual, which provides him with a vision of an upcoming event that may threaten the empire of the High Entia. If he chooses, he may share his visions with others, though protocol states only the emperor may see them. Alvis states that Shulk's way of receiving visions is stronger than his own, as Shulk appears to see dangers that Alvis cannot, although later events suggest this is not entirely truthful.