Armor (Age of Empires IV)

Armor is one of the basic statistics in Age of Empires IV. It reduces damage taken from incoming attacks.

Overview[]

Armor is the primary method of damage reduction in Age of Empires IV, the other being damage resistance. Armor is additive, while resistance is multiplicative. All units and buildings have armor values. These values are always integers greater than or equal to zero. Unlike in other games in the series, no units have 'negative' armor (i.e. have an additive penalty to incoming attacks). There are four different types of armor corresponding to the four different damage types - melee, ranged, fire, and siege. However, no unit or building has siege armor greater than 0, so there are effectively only three types, and siege damage is also referred to as 'true' damage in the editor for this reason (although the ability to add siege armor does exist). The three different effective armor types are all independent, and each unit can have different values for each one. The basic unit and building user interface (UI) only displays two different armor values, which differ depending on the unit type.

Human units display melee and ranged armor
Buildings and ships display fire and ranged armor
Siege engines display melee armor and ranged resistance

However, the third armor type still exists and can be viewed by hovering over the UI to display detailed statistics.

Damage formula[]

The basic damage formula is:

Damage=\max(1,(A_{Base}+U_{Base})\cdot M_{Base}+(A_{Bonus}+U_{Bonus})\cdot M_{Bonus}-Armor)

$A_{Base}$ and $A_{Bonus}$ denote the default base attack damage and bonus damage respectively of the attacking unit.
$U_{Base}$ and $U_{Bonus}$ denote additive upgrades to the base and bonus damage respectively, such as from Blacksmith Technologies or Serpentine Powder.
$M_{Base}$ and $M_{Bonus}$ denote multiplicative (percent-based) modifiers to the base and bonus damage respectively, such as from Elite Army Tactics (both base and bonus), Incendiary Arrows (base attack only), or Chemistry (bonus attack only). They also include debuffs such as from the Camel Unease ability.
$Armor$ denotes the relevant armor of the attacked unit, that is, melee armor when the attacking unit deals melee damage, ranged armor against ranged damage, and fire armor against fire damage.

As can be seen from the formula, armor is the last modifier applied to the damage formula, and it is subtractive on top of all other bonuses or penalties. Therefore, when a unit has both resistance and armor, the incoming damage is first reduced according to the resistance, and then the armor value is subtracted from the reduced damage. Unlike in Age of Empires II, armor does not treat damage from attack bonuses any differently. It is simply treated as additional damage.

Tactics[]

Compared to resistance, which provides the same damage reduction in terms of percentage regardless of the attack damage value, armor has a greater effect when defending against low damage units because it operates in units of 1 damage. For example, against an Archer with an attack damage of 5, increasing ranged armor from 0 to 1 reduces damage by 20%, while increasing it from 3 to 4 reduces damage by 50%, requiring double the amount of hits to kill. By contrast, when facing a Handcannoneer with 38 damage, the same increases in armor will only reduce damage by ~3%. For this reason, armor increasing technologies and abilities are especially important when defending against masses of low-damage ranged units, and conversely, ranged damage upgrades are extremely valuable when attacking with these units. Melee armor upgrades, while still important, are less of a priority because many melee units inherently have higher damage, and micro techniques like hitting-and-running using ranged units, or blocking pathing using other melee units, can be more effective in mitigating melee damage.

Armor and unit types[]

In Age of Empires IV, the heavy unit type is intended to represent heavily armored units. There is no direct relationship between the amount of base armor a unit has and whether or not it has this unit type, but as a rule of thumb, heavy units have both higher-than-normal base melee and ranged armor. The 'default' base melee and ranged armor values for heavy infantry and heavy cavalry are 2/3/4/(5-6) per upgrade level (elite infantry have 6 ranged armor).

Units that have high values of only a single type of armor but zero armor of the other type are typically not considered heavy units. These include Horsemen (and unique equivalents), Tower Elephants and Freeborn Warriors, which have high base ranged armor but no melee armor, and Desert Raiders, which have exceptionally high melee armor but no ranged armor. The only exceptions to this rule at the moment are the Ozutsu, which has high ranged but no melee armor, and the Serjeant, which has high melee armor but no ranged armor. Both these units are considered heavy. There is no corresponding general 'light' unit type for units which are not 'heavy'. There are more explicit types which include the term 'light', such as 'light melee infantry' for Spearmen, but other units commonly considered 'light', like ranged cavalry, do not have an associated explicit 'light' unit type.

The only entities which have fire armor by default are Keeps and Keep-type landmarks. Ships and siege engines, as well as other buildings, can have their fire armor upgraded through various abilities

A full comparison of armor statistics for different types of units can be found on their respective unit classification pages