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How Weapon and Armor Upgrades Work

By burninglegionx - 20th January 2011 - 21:01 PM

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How weapon and armor upgrades work

Each race in StarCraft 2 can upgrade their units’ offensive and defensive capabilities by researching upgrades from their upgrade buildings:

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Engineering Bay: Offensive and defensive upgrades for Terran infantry
Armory: Offensive and defensive upgrades for Terran ground and air vehicles.

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Forge: Offensive and defensive upgrades for Protoss ground units
Cybernetics Core: Offensive and defensive upgrades for Protoss air units

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Evolution Chamber: Offensive and defensive upgrades for Zerg ground units
Spire: Offensive and defensive upgrades for Zerg air units

Many players overlook upgrades because early in the game, spending high amounts of gas on upgrades can delay tech significantly, and later on in the game, one might be too preoccupied with the game and forget about getting the upgrades. But getting the right upgrade at the right time can win you the game, and not getting an upgrade at the right time can lose you the game. More on this later.

For now, let’s see how weapon and armor upgrades work in the game.

Weapon upgrades

A unit’s attack damage is calculated by using this formula:

attack damage = (D + B × L) × n
  • D is the unit's base attack damage,
  • B is the upgrade bouns (e.g. +1, +2, ...),
  • L is the upgrade level (0, 1, 2, 3), and
  • n is the number of individual attacks per "volley" or "charge".
Example: The Zealot. The Zealot's base damage is D = 8, and he does n = 2 stabs in one attack. The upgrade bonus is +1. So we have:
  • Unupgraded (level 0): 8 × 2 = 16
  • Level 1: (8 + 1 × 1) × 2 = 18
  • Level 2: (8 + 1 × 2) × 2 = 20
  • Level 3: (8 + 1 × 3) × 2 = 22

Armour upgrades

Armor upgrades reduce the amount of damage taken per individual attack by subtracting a certain amount of damage from each attack. In the above example of the Zealot, an unarmored unit would take 16 damage from an unupgraded Zealot, while a unit with +1 armor would only take 14 (7 per stab), a +3-armored unit would take 10 damage (5 damage per stab), and so forth. (Note that every attack will cause a minimum of 0.5 damage regardless of armor.)

As this example shows, armor upgrades are more effective against units that attack multiple times than against units that use single attacks.

Someone people argue, "upgrades in StarCraft 2 add only 1 to 2 damage or armor to my units   that sounds fairly useless." Indeed, upgrades only add a comparably small value (usually +1 damage or armor) to your units’ stats, but that 1 unit of damage or armor can turn the tide of a battle, because if you get the weapon upgrades, your whole army will have a higher damage output than your opponent's army, and if you get defensive upgrades, it reduces your enemy army’s overall effective damage output.

Upgrades are especially useful if you hit that “critical upgrade”. For example, a Zealot with ground weapon upgrade level 1 will be able to 2-shot a Zergling instead of requiring 3 shots. Even though the upgrade only adds 1 damage per attack, it increases a Zealot’s combat effectiveness against Zerglings by 33%! The most common critical upgrades are listed on the following pages.