Harass or Harassment is the act of using a small number of units, usually with superior mobility, to cause damage to the enemy without a large engagement. Harassment is usually targeted at damaging or disrupting the enemy's economy, sometimes even his or her production, all-in order to throw the opponent off.
There are a few points to a base harass. The first and most common form of harassment is to try and gain an economical advantage by killing off your opponent's workers or just causing them to stop mining all together. This furthermore delays enemy production and can create a significant economic advantage in a match. Second, would be to destroy a key building or unit (Pylon, Supply Depot, Overlord) to supply block your opponent. This forces the enemy to waste more minerals in order to recover the supply lost while you are continually creating units and getting ahead in army size.
However, harassment can be effective without actually killing any of the opponent's units or buildings. Just the fact that that the opponent is forced to focus on defending instead of their macro or build order to avoid being thrown off on their initial game plan is enough to give the harassing player an advantage. Using mobile harassing units against an opponent is an effective means of exploiting the lack of enemy mobility, such as Terran mech play, or can be used to distract an opposing force for a significant advantage in a direct engagement.
Common Methods of Harassment
- Void Ray harass is commonly used against both Terran and Zerg opponents. Void Rays can be game ending if the opponent does not have anti air by the time they arrive and they can do large amounts of damage to both units and buildings.
- Phoenixes are an excellent harassment unit once they have reached a certain number. They can be used to pick off Zerg Overlords as well as use their Graviton Beam ability to pick up and kill workers. Their fast movement speed allows them to fall back before taking significant damage.
- High Templar and Colossus drops with the use of a Warp Prism are also commonly used to kill enemy workers because of their splash damage.
- Dark Templars can annihilate an entire mineral line worth of workers in seconds if the opposing player does not notice them in time or lacks detection.
- Zealots can be sent into the opponents mineral line in a small group to kill workers and delay mining. This only works when the opponent has their army out of position and is therefore best used in the lategame when your opponent is more spread out, when the opponent is attacking you or when you are being contained.
- Oracles have brought a new form of Protoss harassment in HotS, using their fast movement speeds and energy based Activate Pulsar Beam to quickly tear through enemy worker lines.
- Adepts can quickly kill workers and other light units and move between different bases with their Psionic Transfer.
- Mutalisks are a very strong harassment unit due to their mobility, high damage output and splash damage. Zerg players frequently use them as a "surprise tactic" by transitioning to Mutalisks after they have opened with an other unit combination and try to exploit the fact that the opponent may not have adequate anti-air defenses ready.
- Infestors can be used in conjunction with their Fungal Growth ability to damage and possibly destroy large numbers of workers. Because however a single Fungal Growth is not enough to kill a worker they do not see much use. The damage from Fungal Growth, however, can be combined with a few Infested Terrans to destroy the workers. Also, only one Fungal Growth is needed to kill larva.
- Roaches with the Tunneling Claws upgrade are sometimes used to sneak past an opponent's defenses if he lacks detection and unburrow near his mineral line targeting workers.
- Banelings have excellent splash damage and are often used to sneak into an enemy mineral line. They can also be dropped from an Overlord directly on the workers, avoiding any base defenses that may exist. When you have the +2 melee upgrade it only takes one Baneling to kill a Probe or a Drone (SCVs still take two Banelings to die).
- Zerglings have an ability to sneak around the enemy's army, and attack any unguarded mineral line. A common thing is in ZvZ where micro with Queens and Zerglings is of huge importance since a run-by into the main mineral line can result in heavy Drone losses. If you have a Baneling Nest you can hide 2-6 Zerglings in your opponent's base while attacking his Drones and turn them into Banelings. After he cleans it up, you simply wait, and when he gets his Drone count up, you distract him with some Zerglings and explode to kill a huge amount of Drones again.
- A single Lurker can effectively shut down the enemy mineral line until detection arrives.
- Medivacs are used to drop units at an undefended part of an opponent's base or near his mineral line to cause damage without taking much damage. Drops are the most commonly used harassment method in the Terran arsenal since Medivacs are almost always a part of the Terran army.
- Hellions offer great maneuverability and their splash damage can destroy workers extremely quickly.
- Banshees have great air-to-ground damage and can cause significant damage if no anti-air is present. Their usefulness is prolonged by the Cloak upgrade, forcing the opponent to get Detectors.
- Vikings are often used against Zerg to hunt Overlords. Their big advantage however is their ability to land, damage a remote part of an enemy base-preferably the mineral line- and lifting off again before the enemy can react.
- Reaper harass is a very common Terran opening but can also be used in the mid and late game. Reapers can enter and exit a player's base extremely fast due to their Jet Pack ability, and constantly be a threat due to their quick health regen.
- Auto-Turrets are often used by Ravens behind the enemy mineral line.
- Ghosts can be used to either Nuke the enemy base or just kill workers, abusing the Ghost's Personal Cloaking ability.
- Widow Mines are a new unit in HotS which are commonly used early game to be dropped into worker lines to destroy harvesters as well as force detection.
- Liberators can quickly take out many workers by using their defensive mode on the enemy mineral line. Until anti-air arrives, every worker trying to mine will be one shot. They also one-shot larva and, given +1 attack upgrades, two-shot queens.
Other forms of Harassment
Players frequently try to block an enemy building from beginning construction in order to delay it and throw their opponent off. This can be done by simply moving a worker at the location where the opponent wishes the building to be placed during scouting but there are other ways as well.
Cheap buildings like Pylons or Supply Depots are often built at possible expansion locations in an attempt to delay them. Zerg players may also use the Overlord ability Generate Creep, Creep Tumors or burrowed units in order to deny building placement.
- Reactor Hellion Expand (vs. Zerg) A very common TvZ opening-based on Hellion harass.
- Nuke Rush (vs. Zerg) An unorthodox build aimed at getting a fast Ghost with Nuke.
- Turbo Reaper (vs. Protoss) What used to be the most common TvP opening, a very fast Reaper is obtained with the sole purpose of killing Probes.
- Cauthonluck cheese A fast Banshee opening.
- Thor Drop Rush (vs. Zerg) A common TvZ harass-centered build.
- Dark Templar Rush and Dark Templar Fast Expand (vs. Terran) are builds-based on keeping the opponent occupied with DT harass while the Protoss player expands or masses an army.
- 1 Gate Stargate (vs. Zerg) can be used for both fast Void Rays or Phoenixes to force the Zerg to defend against aerial harassment.
- 1 Base Muta (vs. Terran). Fast Mutalisks are obtained to force the Terran player to play defensively and punish greedy play.
- TheLittleOne(Z) vs Kolll(Z): TLO uses Infestors with Fungal growth to successfully harass Koll's mineral line. (2010w16 - Razer SC2b Domination Invitational - Round1)
- Day daily on White-Ra vs. Maka on Incineration Zone: White-Ra manages to come back from a very difficult position by constantly Storm Dropping Maka.