Damage (XC1)

Damage is the means of reducing an opponent's HP to zero in Xenoblade Chronicles. s and s deal varying amounts of damage, combined with the user's stats and equipped weapon.

Damage formula
The damage formula is slightly different depending on whether a party member is attacking an enemy, or the other way around.

For a party member as the attacker: (stat + wpn) * art * (1 - def) * modifiers * lvl * block * casual For an enemy as the attacker: (stat - def) * art * modifiers * lvl * block * casual In these formulas: Finally, the damage value is rounded down if it is not an integer.
 * stat is the relevant stat of the attacker: for physical attacks and  for ether attacks. Stat-manipulating effects are applied here. In general, all additive boosts (e.g. +15) are applied before any percentage boosts (e.g. +15%).
 * wpn is the weapon's attack. It is a random number between the weapon's minimum damage and the weapon's maximum damage. Weapon-manipulating effects are applied here.
 * In the original Wii and 3DS releases, a bug causes the maximum damage to never be above the minimum damage plus 99. This is fixed in the Definitive Edition.
 * art is the arts multiplier.
 * For party members, most auto-attacks have a fixed 1.0 multiplier, and most arts have a single multiplier. This is because any randomness is already applied by the weapon factor.
 * For enemies, all auto-attacks have a random range of ±10% (from 0.9 to 1.1), and arts have a similar amount of randomness (e.g. having a power between 2.3 and 2.5).
 * def is the defence of the target. Whether it is physical defence or ether defence depends on the attack being used. Effects that manipulate defence are applied here, but not those that manipulate damage taken.
 * For party members, it is the sum or their personal defence and the defence of all equipment they are wearing.
 * For enemies, it is the multiplier of their relevant defence stat, if the attacker is placed in the correct direction. Enemy defence cannot be stronger than 90% (taking only 10% damage) even if set higher.
 * modifiers is the sum of effects caused by buffs, debuffs, skills, s, and so on. It also includes the multiplier of 1.25, if applicable. This value cannot go any lower than 0.1 (10%).
 * lvl is the level correction value, skewing the battle in favour of whichever side is higher-levelled.
 * block is 0.5 if the attack is blocked, otherwise it's 1.0.
 * casual is 1.0 if Definitive Edition's is disabled. If enabled, it's 2.0 for party member attacks and 0.5 for enemy attacks.

If the target is immune to the attack, the result of the damage formula is skipped entirely - the target takes only 1 damage, or 0 if the attack is blocked. This is altered in the Definitive Edition, where the damage done is reduced to 1 as part of the formula. This results in a few changes:
 * Damage bonuses such as those of still apply, so Shulk will deal 2 damage instead of 1 from behind.
 * The damage dealt by debuffs such as bleed is, instead of always being 1 per tick, equal to the debuff's normal damage of "a percentage of the triggering damage". As damage always rounds down, this means each tick does 0 damage unless the debuff's value is 100%.

Outside of battle
Not all damage is sustained from enemy attacks; wandering into dangerous areas or falling from too high will also inflict damage. These sources of damage do not stop when in battle, so it is important to avoid them when possible while fighting. Computer-controlled party members cannot be killed by fall damage or terrain damage unless a fight is ongoing; they will drop to 1 HP instead.

Fall damage
Dropping from one surface to another within 10 metres is safe. For every 10 metres added to a fall, the damage taken is increased by 20% of a party member's max HP. gems protect against the damage taken, but only from falls that are survivable; a height of 50 metres is lethal regardless.

Terrain damage
Various liquids are hazardous to swim in, dealing damage based on max HP every few seconds. Auto-healing does not activate when in such a substance, and the map and menu cannot be opened if the controlled character is in it. gems protect from this damage.