War Assets are assigned a point value, indicating Total Military Strength, which is then multiplied by a Readiness Rating to produce the galaxy's Effective Military Strength, which determines success in the final battle against the Reapers. They are earned in direct tie to what occurs in the game, whether it be events happening in the background or the missions which the player actively participates in. War Assets may also be obtained by scanning planets in systems controlled by the Reapers on the Galaxy Map but it poses the threat of being detected and terminated by the machines.
War Assets and their total military strength can be inspected using the War Terminal located in the War Room on the second deck of the Normandy.
The readiness rating is presented as a percentage of the collected War Assets that contribute to the galaxy's Total Military Strength. War Asset's true value is attributed to the Total Military Strength, but is then multiplied by the Readiness Rating percentage, resulting in the Effective Military Strength. The readiness rating is increased by participation in the Galaxy at War system, which includes:
- Mass Effect 3 Multiplayer
- Mass Effect: Infiltrator (No longer available in Apple's AppStore or Google's Play Store since 2015)
- Mass Effect 3: Datapad (No longer available in the app store as of June 6, 2013)
- N7 HQ (Now incorporates functions previously on Datapad)
Participation in Galaxy at War is encouraged to maximize the Military Strength given by each War Asset, as playing single-player alone will limit EMS by 50%, or half, of the overall War Assets score the player has acquired. There are 8370 total War Assets available in the game without downloadable content, but this number cannot be reached as it includes War Assets that are restricted to specific outcomes of player decisions, including saving Kaidan Alenko or Ashley Williams, saving or sacrificing the Citadel Council, and spreading or sabotaging the genophage cure. As such, the highest obtainable War Assets score is approximately 7500. If the multiplayer mode is not played, the player will only be able to acquire ~3750 EMS, which is less than the ~4000 EMS necessary to experience all possible endings.
Downloadable content for Mass Effect 3 significantly affects the War Assets system. Mass Effect 3: Extended Cut lowers the EMS required to achieve all possible endings from ~4000 to 3100. Mass Effect 3: Leviathan features an additional 620 War Assets for the player to obtain, Mass Effect 3: Omega features an additional 405 War Assets, and Mass Effect 3: Citadel adds 70 points to the Alliance Frigate Normandy SR-2 War Asset.
In Mass Effect 3's multiplayer mode, completing matches adds to the player's overall readiness rating. While the player may choose the map they wish to play, this only puts readiness points towards the associated theater of war. Typically, if a specific map is chosen, 8-9% readiness is added to that theater, while if "Unknown Location" is chosen, aside from the XP Bonus, 3-4% readiness is added overall. The readiness rating is averaged from the ratings of all the theaters, meaning if "Unknown Location" is chosen, all theaters will receive a 3-4% boost. If a multiplayer mission fails in the second half of the match (after Wave 5), 2% will be allotted to the player. Readiness will not fall as long as the PC/console is kept offline.
Sword, Shield, and Hammer
When the mission Priority: Earth is started, all gathered War Assets combine into three different groups, codenamed Sword, Shield and Hammer. Sword and Shield consist of all allied fleets and starships, and Hammer consists of all ground forces. When Sword attacks the Reaper fleet above Earth, it acts as a distraction to allow Hammer to land on Earth and engage the Reapers on the ground to aid Admiral Anderson's resistance forces. Meanwhile, Shield is held in reserve to escort the Crucible into position to dock with the Citadel.
Depending on the number of War Assets gathered and their combined military effectiveness rating, Sword and Hammer will either begin taking heavy losses quickly or be able to hold their own until the end of the mission. The survival and continued defense of Sword and Hammer are pivotal to the success of the final mission. For example, high EMS results in enough suppressive fire for the Normandy to quickly land and extract squad members to safety, as well as allowing the Crucible to dock with little to no damage taken.
- Galaxy at War
- Search and Rescue for War Assets obtainable directly through the Galaxy Map