Army composition basics

In Direct Strike, decisions in army composition often determines the outcome of a game in the long run.

This article covers basic notes on optimizing your army composition.

See also:


 * Protoss Strategy
 * Terran Strategy
 * Zerg Strategy

Units
Units are the basic building block of your army.

Unit Roles
A unit role is the intended purpose of a specific unit. There are three broad roles which units are capable or effective at fulfilling. They are damage dealers (also known as "dps"), damage takers (also known as "tanks"), and support. Most units have multiple uses suitable for different encounters.

These roles can be further split into Ground and Air. A player is effectively fighting two wars simultaneously, both ground and air, and the winning side can help the other one. For instance, a player with Air dominance is free to make Air-to-ground units which may be effective against the opposing player.

Basic Role composition
Generally, it is up to the judgement of the player to assess the effectiveness of their army composition against the enemy forces. Some generally observed practices are as follows:


 * If your army is not surviving long enough, add effective damage takers.
 * In a TvT, Reapers need Marauders to take damage from enemy Reapers.
 * In a PvT, High Templars need Immortals to take damage for them so that they could survive long enough for energy to unleash their Psionic Storm.
 * In a ZvZ, Hydralisks need Roaches to survive long enough against enemy Queens to be able to do enough damage to kill them.
 * If your army is surviving but not killing the enemy wave fast enough, add damage dealers.
 * In a ZvZ, if you have lots of queens but can't kill anything, add Hydralisks or Ravagers behind them.
 * In a TvP, if your bio isn't surviving long enough against enemy Zealots, make Hellbats.
 * In a ZvT, if your queens are dying to mass ghosts, add Mutalisks so they snipe these cheap units instead.
 * If there are particular scenarios or niches where support units could cost-effectively affect unit composition, add them.
 * If the enemy has cloaked or burrowed units, add detection.
 * If the enemy units are small and many, add AOE damage.
 * If the enemy has air units, make anti-air.
 * ... and the list goes on.

Role Switches
Roles may frequently switch during the course of a game. The ability to plan your unit role switches throughout the course of the game is crucial for your success in the game.

Examples:


 * In a Zerg vs Protoss encounter, Queens are effective damage takers in the early game against adepts and stalkers. As the game progresses, they are also effective damage dealers against Void Rays. When the Zerg push past mid into the opposing side, queens become an effective support unit that heals a large amount over time.
 * In a Protoss vs Protoss mirror match, Archons are effective damage dealers against enemy Adepts. If the enemy makes Void Rays, then Archons will become an effective damage taker against the Void Rays, allowing your stalkers to do their damage without being melt by them.
 * In a Protoss vs Terran encounter, Adepts are both effective damage dealers and damage takers against enemy light bio units such as Marines and Reapers. When the Terran starts to add Marauders to their army, Adepts become only effective as damage takers against Marauders, and the Protoss must add Stalkers to effectively damage the Marauders. As the game progresses, Adepts may switch to a pure damage-taking role because of their lack of range.
 * In a Terran vs Zerg encounter, Marines are effective damage dealers against Zerglings, but are not effective as damage takers. With a few Marauders in front of the line taking damage from the Zerglings, the Marines and Marauders team could beat a Zergling army that are otherwise impossible to beat with Marines alone. As the game progresses, Marines typically switch to an anti-air damage role, protecting your Liberators against opposing Mutalisks.

As unit roles could potentially switch throughout a game, ideally you should plan out your units composition to avoid over-committing to units which could become totally ineffective at their intended roles over time.

Should no effective roles be foreseeable in the remainder of the game for a specific unit, the unit should be sold for minerals which can then be used to deploy more units that are more effective at fulfilling the required roles. This situation however is often quite costly and should be avoided if possible.

For example, in a Zerg vs Zerg mirror match, as the opposite side techs to Tier 3 with Vipers out, Mutalisks no longer serve their roles as aerial damage takers. You could opt to sell a portion of them, leaving a couple to trigger the Vipers' Parasitic Bombs (so that they don't hit your Corruptors - ineffective if they're manually cast.)

Counters
When one unit is effective against the intended role of another unit, it is known as a counter.

Examples of counters:


 * Roaches are effective damage takers for the Zerg ground army. Marauders however, does extra damage to Roaches, and thus the Roach cannot protect the Zerg ground army against Marauders. An alternative must be found to fulfill that role.
 * Marines are effective damage dealers for the Terran army. Reapers could blast the Marines and temporarily disable their attack and scatter their formation. Thus Reapers is a counter to Marines.
 * Archons is a counter against Void Rays. While Archons do not kill Void Rays as effectively, the intended purpose of Void Rays are often to do effective damage against enemy armored units. Since Void Rays cannot effectively damage Archon, they're a counter to this role.

Sometimes the same unit could serve as a counter only if the enemy unit is being used for a specific role. For different roles, they are not effective.


 * Zealots are effective damage dealers against enemy queens. But if the intended purpose of the Queens is to survive and stack with the next wave, Charge actually reduces the distance that Queens travel, which is detrimental to their goal and helpful for the Zerg.
 * High Templar is not an effective counter against Ravens when the intended purpose of Ravens is to survive and stack. They are effective however if the purpose of Ravens is just to deal damage, since Feedback prevents Turrets from being cast.
 * Infesters effectively counter Archons when the intended purpose of Archons is to deal damage to a group of long-range Zerg units. As they're slowed, they are unable to reach the Zerg army in time before they're killed. However Infestors are ineffective if the intended purpose of Archons are different.

The key in designing and deploying your counter thus lies with first understanding the intended purpose of the enemy unit. Many common strategies involve switching the roles of one unit for another, while tricking the opposing player for an ineffective counter for its intended role.

Examples:


 * Getting stalkers not to do damage and win a wave, but to survive and stack with the next one.
 * Making Mutalisks not to deal damage but to take damage for the Roach/Hydras in a subsequent wave.
 * Making Marines not to do ground damage, but to pre-empt an aerial Mutalisk attack, so the Terran player is free to make ground units.

Formation
Your intended units should be placed in an appropriate location relative to your army. For instance, damage takers should be in front and damage dealers at the back.

Melee vs range units
As the space on the island is limited, Melee units generally suffer from a penalty as the size of both armies grow.

Upgrades
When considering upgrades, keep in mind the (oftentimes better) alternative, which is to get an additional unit.

Suppose you have 3 Marines. With 100 minerals you can get +1 attack upgrade, or 2 more Marines. In a fight, 5 Marines will beat 3 Marines with +1 upgrade.