//If you're new to USC, you might want to check out the [[step_by_step_tutorial|Step-by-Step Tutorial]], too!// ====== Combat ====== * [[#Preamble | Preamble]] * [[#Combat properties | Combat properties]] * [[#The Attack Value | The Attack Value]] * [[#The Defense Value | The Defense Value]] * [[#Critical hits | Critical hits]] * [[#Doing damage | Doing damage]] * [[#Additional effects | Additional effects]] * [[#Defense mode | Defense mode]] * [[#Covers | Covers]] ---- ===== Preamble ===== Combat is obviously the most important part of the game. Understanding the combat mechanics in detail is one of the key steps towards developing a good battle strategy. It is highly advised to carefully read this chapter even if you're not really into numbers. On the other hand, none of this information is required to be able to equip a squad and start experimenting with how things work -- in real action! ===== Combat properties ===== The USC //combat system// uses many different variables to evaluate the result of an attack. As there's always an //attacker// and a //target (defender)//, combat variables can be divided into //attack// and //defense properties//, the latter being reasonably fewer. //Defense properties// are (properties of target/defender): *[[basic_concepts#Armor Rating|Current Armor Rating]] **//[AR]//** *[[#The Defense Value|Defense Value]] **//[DV]//** (in melee) *[[#The Defense Value|Static Defense Value]] **//[SDV]//** (when being a ranged target) *[[#The Defense Value|Dynamic Defense Value]] **//[DDV]//** (when being a ranged target) *[[units_detail#Stamina|Stamina %]] //Attack properties// form two major groups, one being the attributes of the attacking unit (//attacker// properties), the other the properties of the weapon / ammo / attack mode used (//weapon// properties). //Attacker properties// are: *[[#The Attack Value|Precision]] (in melee; also called Base Attack Value, //BAV//); may incl. modifier from attack mode *[[#The Attack Value|Static Precision]] **//[SP]//** (in ranged combat); may incl. modifier from attack mode *[[#The Attack Value|Dynamic Precision]] **//[DP]//** (in ranged combat) *[[units_detail#Reaction|Reaction %]] //Weapon specific attack properties// are: *[[#Doing damage|Critical Chance]] **//[CC]//** (also called Critical Threshold, see later) *[[#Doing damage|Critical Damage Factor]] **//[CDF]//** *[[#Doing damage|Maximum damage]] //[maxDmg]//, from which the Minimum (base) damage //[minDmg]// is also calculated; may incl. modifier from ammo //Attack mode /+ ammo specific attack properties// are: *[[#Additional effects|Armor penetration]] **//[ARP]//** *[[#Additional effects|Impact force]] *[[#Additional effects|Tranquilization]] *[[#Additional effects|Ignition chance]] (hidden on ATAC) *[[#Additional effects|Corrosiveness]] (hidden on ATAC) *[[#Additional effects|Biohazard]] (hidden on ATAC) Although //not a property//, but worth listing: *[[#Doing damage|Damage Factor]]: multiplier of the base damage *[[#The Attack Value|Target range]] (in ranged combat): a modifier for Static Defense Value *[[#The Defense Value|the To-Hit Value]] and the result of the Attack (To-Hit) Roll ===== The Attack Value ===== The AV is a complex variable that represents the ability of the attacker to //hit the target//. Doing so in melee combat or from a distance is totally different, thus the calculation of the AV is not the same. AV is then //subtracted// from the target's Defense Value to get the //To-Hit Value//, against which the result of a //20-sided die roll// (1-20) is tested to determine whether the attack was successful or not. This means that even under the exact same circumstances attacks have a chance to be "more or less precise", to hit or to miss. //Melee Precision (Base Attack Value)// = //Melee combat %/20// (0-5) + //Reaction %/20// (0-5) + //attack mode// (weapon) //precision// (0-5). //Ranged Precision// has two components. //Static Precision// measures the basic accuracy with the weapon, based on proficiency and "static" circumstances, such as target range, light level, or obstacles in the way. //Dynamic Precision// refers to the attacker's ability to aim at moving or otherwise "erratic" targets, where very quick adaptation is required. The values are independent of each other per se; i.e. having good reflexes doesn't help to hit a faraway target, while being able to aim precisely at a static target doesn't necessarily mean an ability to hit fast, moving ones. (Note: the latter ability is less important, generally speaking, as the top speed of units is limited.) //Ranged Static Precision// = corresponding //Small/Heavy arms %/20// (0-5) + //attack mode// (weapon) //precision// (0-5) {+ bonus from //targeting computer// (4/8)*}. * If enabled, gives +4 SP under normal circumstances and +8 SP in darkness or against a cloaked unit (~ counters target's Static Defense Value //only// from these sources). //Ranged Dynamic Precision// = //Reaction %/20// (0-5). ===== The Defense Value ===== It measures the target's ability to defend itself against the attack by means of dodging, evading, or deflecting. DV does NOT protect against damage but gives a chance to //avoid being hit//. Defense is //successful// if the To-Hit Value (DV decreased by AV) is the //same as or higher than// the To-Hit (Attack) Roll //and// the attack was //NOT a critical hit// (see later). //Melee Defense Value// = //Melee combat %/10// (0-10) + //Reaction %/20// (0-5) + current //speed// (0-5) + //cover// (0-6) {+ //Defense Mode// (0-27)} {+ //cloaking// (8)}. In //ranged combat//, the attacker's Static Precision is subtracted from the SDV, and the Dynamic Precision is subtracted from the DDV (both are clamped at 0), then these two results are added together to get the //To-Hit Value//. //Static Defense Value (SDV)// = //range// (1/grid) + //cover// (0-10) + //darkness// (0-10) {+ //cloaking// (8)}. //Dynamic Defense Value (DDV)// = //Reaction %/20// (0-5) + current //speed// (0-5, capped at range). ===== Critical hits ===== As stated above, by standard an attack is considered a //successful hit// if the result of the //Attack Roll (1-20)// is //greater than// the //To-Hit Value//, which is the target's Defense Value decreased by the attacker's Attack Value (Precision). There is a very important exception, though. Every attack has a chance to score a "//critical hit//". Critical hits are by definition considered //successful hits//, absolutely irrespective of the To-Hit Value. This chance is determined by the //Critical Threshold//, a value that is based on the actual weapon's own Critical Threshold attribute and a few modifiers (proficiency, active mods, etc). The value of the Critical Threshold is generally between 13 and 20. If the //Attack Roll// is //equal to or greater than// this, the attack is a critical hit. //Critical Chance// is the exact same thing, just expressed in the other way: a CT of 20 means a CC of 5% (1:20), 16 means 25% (5:20), and so on. Beside being a granted hit, critical hits have other bonuses. They //multiply the Damage Factor// (default 1.0×) of the hit by //2.0// (martial & small arms) or //1.5-4.0// (heavy arms), which results in increased damage. (Prototype weapons may have a further bonus.) In addition, a critical hit always //damages the target's armor// by //2//. Critical hits cannot be fully averted, but [[units_detail#Specializations|Melee combat mastery]] decreases the attacker's chance in close combat by //5%//, and the usage of a //cloaking device// reduces their Total Damage Factor to //0.35×// (//0.6×// against heavy arms). Also, on lower difficulty levels lesser aliens have no chance of scoring a critical hit. Critical hits have a chance to //return// some APs to the attacker. This effect is called //critical AP-rebound//. It symbolizes situations where the attack could be conducted faster than it was expected or where the result of the attack altered the combat situation in a sudden, but positive way. The chance for AP-rebound is //Reaction %// per hit (area attacks thus have good AP-rebound effectiveness). Only hitting //units// can confer bonus APs. The amount of APs returned per unit can be //1-4//, based on luck and the [[units_detail#Reaction|Reaction skill]]. ===== Doing damage ===== Each attack mode has a //maximum damage range//, shown as e.g. 10-20. This is the //maximum base damage//: the maximum damage the weapon can do with the default 1.0× Damage Factor. Based on the respective //combat skill//, attack modes also have a //minimum damage//. It is also given in a range, the lower bound being the absolute minimum damage you can do. Thus, in fact, the real damage range of an attack is between the lower bound of minDmg and the upper bound of maxDmg. After the actual base damage is determined by random methods, //Damage Factor// is applied to it -- a multiplier with a default value of //1.0//. Modifiers: *Using scattering fire modes ([[weapons#Sweep|sweep]]) at a minimal distance (1) increases DF by //0.5// (mainly affects the [[shotgun|shotgun]] and the [[minigun|minigun]]). This is applied before: *//Critical hits// multiply DF by //2// (martial & small arms) or //1.5-4.0// (heavy arms, randomly) (the result will be 2.0/3.0 or 1.5-6.0, see above). *100% of [[units_detail#Small arms|Small arms]] increases //critical hit// DF by a further //1.0//. *Prototypes with the //Critical Damage Factor// property further increase //critical hit// DF (by 0.5 or 1.0). *Total DF of a //critical hit// is reduced to //0.35// (martial & small arms, all aliens) or //0.6// (heavy arms) if the target is //cloaked//. Then, the resulting //total damage// (e.g. 24 for a base damage of 12 and a DF of 2.0) is tested against the target's //[[basic_concepts#Armor Rating|Armor Rating]]//, which //reduces// it with its current value. It is also called the "Damage Threshold" because attacks with equal or lower damage are totally absorbed. The final damage is subtracted from the target's //Health Points//. If it reaches 0, the target is killed/destroyed. Some attack modes have //area damage//. The center (actual) target gets 100% of the possible base damage, the others a smaller amount as the damage //decays// with distance. Note that every target affected gets a //distinct// To-Hit and Damage roll: some may dodge the attack, some may not, some receive more damage, some less, some a critical, some not. The amount of //distance damage decay// varies with weapons, please feel free to experiment with. The //damage of aliens// in Single Mission mode is //reduced// to 0.5×-0.9× of damage by rules on difficulties lower than ULTIMATE, respectively. ===== Additional effects ===== Units that survive an attack may suffer additional forms of "damage". Based on the //Armor penetration// property, attacks have a chance to damage the current //Armor Rating// of the target by //1//. The chance for this is //ARP : AR// (e.g. an attack with an Armor Penetration of 5 has 25% chance to damage an Armor of 20, whereas an ARP of 20 or more *will* damage it). //Critical hits// automatically damage the Armor by //2//. The damage to the Armor is not taken into count until the next attack. The chance of Armor Rating loss for marines when the armor is penetrated is reduced to 1:3-2:3 on difficulties lower than ULTIMATE. It does not apply to critical hits. Hits can also //"slow down"// and/or //knockback// their target by //1 grid//. These effects are based on the attack's //impact force [IF]//. Any attack has //IF %// chance to cause //1 Action Point loss// for the target's //next turn//. Hits also have the same chance to //knock// the target //back// if it's //Stamina// is low enough and it is not protected against this effect. If a knockback occurs and there's no more space behind the target unit, it loses //2// (additional) //APs// for its next turn, instead. Attacks with an area effect may knock the target back with multiple grids, as the targets become a target again while being "moved" in the target area. They may also suffer additional damage this way! //Tranquilization//, if the attack mode has any, is applied in two steps. //33%// of the effect is applied automatically when the target is hit. The remaining //67%// is only applied if the hit does at least 1 damage (i.e. passes through Armor). The tranquilization done to the target is //cumulative// for the turn, and comes into effect at the beginning of its next turn. //Incendiary// attacks (that of with an //ignition// value) have a chance to set the target ablaze. This chance cumulates with each hit having an ignition value, but only incendiary attacks can possibly ignite the target (i.e. you can "buff up" a target's chance of burning, but you still need another incendiary hit to set it ablaze, normal ones won't do, even with the ignition chance buffed). Any //biohazard// or //corrosion// done by hits simply increases the target's total currently carried biohazard/corrosion by value. //Critical hits// can cause //bleeding//. The amount of this is //damage/10// (floored). Bleeding decreases HPs at the beginning of each turn. ===== Defense mode ===== Defense mode is a very important tactical option that means using up all remaining Action Points in the current turn to boost Defense Value until the next turn OR enable the possibility of "opportunity attacks" in the enemy's turn. It also //reduces incoming damage//. //Activating// Defense mode for a unit costs //at least 5 Action Points// under all circumstances, while any //surplus APs// mean more defense bonus or more "opportunity" Action Points. Going into Defense mode also requires //at least 20 current Morale Points!// It can be done with any weapon, though there's the aforementioned super-important difference between melee and ranged Defense mode. //Melee Defense mode// is in effect when you have a melee //weapon or attack mode// selected. (Weapons capable of a melee Defense mode are: [[katana|Katana]], [[chainsaw|Combat chainsaw]], [[combatrifle|Combat rifle]]--in melee mode, [[energyrifle|Energy rifle]]--in melee mode, [[feline|Energy blade]]--not in "Overcharge" mode.) Melee Defense mode is //passive