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Kalath Intercession (since reactivated)
The plural of colossus is colossi.
The colossus is an antiquated protoss war machine, dating back to the Kalath Intercession. It is a towering construct, striding across the battlefield on four tall, slender legs which give it an extremely high level of mobility. The great height of the machine allows it to step up and down cliffs and other steep elevations with little difficulty, and gives it a dominating field of fire. The colossus's slender legs were designed to carry its massive weight with ease, while allowing for the traversal of rough terrain and steep elevations. Its towering four leg configuration has multiple gyro-stabilizers to keep the Colossus stable while moving and firing, and also denies the enemy the advantage of higher ground.
The colossus is feared for being a war machine, and some protoss believe they cannot be controlled and could turn against them.
The heavily armored hull of the colossus carries two powerful thermal lances: one mounted on each side of its body. Complex focusing and targeting systems are used to pinpoint the continuous damage output of the thermal lances for optimal efficiency. The targeting system uses an AI, along with gravity-sensitive gyroscopes, to analyze target composition, and predict their movement patterns. This ensures the thermal lances' beams will sear a path of maximum destruction among enemy forces, cutting a fiery swathe of destruction through multiple enemies with each firing cycle. The targeting system is so precise that the colossus can fire its weapons point blank without risk of damaging itself.
The lances themselves fire beams of superheated plasma that quickly incinerate scores of enemy ground targets, able to reduce a group of marines to ashes in an instant. While powerful, colossi weapons present a design issue, as their range is somewhat limited. Khalai phasesmiths built an extended thermal lance with enhanced airflow that could operate at higher temperatures, increasing beam velocity and effective range without loss in power output.
The colossus is unique in that it was created purely as a war machine, in contrast to most protoss automatons which were mainly created for industrial and/or resource gathering purposes. Such a trait was demonstrated by the mass slaughter carried out against the kalathi, appalling the protoss. As such, the Conclave outlawed the manufacture of colossi, and existing machines were deactivated before being sealed away. Some were sent to distant asteroids and uninhabited moons. Others were stored on Aiur, some underwater, awaiting a reactivation signal. They weren't reactivated in time for the war on Aiur because it would take too long.
The war against the zerg, however, prompted the return of the colossi to the protoss arsenal. In 2503, the protoss began collecting them using coordinates collected from a preserver, despite misgivings. The colossus has since become synonymous with the protoss by the citizens of the Terran Dominion.
In 2504, Dark Prelate Zeratul traveled to Aiur and reactivated some colossi as part of a mission to study the body of the deceased Overmind. Later that year the Tal'darim used them as well in their defense of a xel'naga temple on Xil.
In 2506 colossi were deployed in the Reclamation of Aiur to clear out the warp conduits of zerg forces. Later in the End War they were used to aid in deactivating the shield around Cybros. Colossi developed by the Purifier program were later added to the Daelaam arsenal, employing more destructive incendiary weaponry than their Khalai counterparts.
Targeted as both an air and ground unit. Can step up and down elevations.
Colossi are not strong for cost and require support, such as a front line of zealots. They are strong against marines, zealots, hydralisks and zerglings, but weak against thors, immortals, ultralisks, and anti-air units like the viking, phoenix, and corruptor.
Height and Climbing
The colossus appears to step over ledges due to StarCraft II's inverse kinematics (IK) system. It can climb ledges only one level at a time and is blocked by taller cliffs. It can also step over smaller friendly units, but not other colossi or obstacles. Like other massive units, the colossus can collapse a Force Field simply by being ordered to move through it.
The colossus' height enables anti-air attacks, such as those of the missile turret, to strike it (even though it is a ground unit). Blizzard has confirmed that this is because the colossus is so tall that it counts as both a ground and air unit for the purpose of what attacks are able to hit it. If an attacking enemy unit (such as the thor) which can attack both ground and air units attacks a colossus, it will use whichever attack is stronger against the colossus.
The colossus attacks only ground units.
The attack animation is a sweeping beam, with the animation taking about a second to complete. All targets continue to take damage simultaneously. The attack always strikes a linear area perpendicular to the direction the colossus is facing. This allows for a fine degree of control.
The attack does linear splash damage which is very effective against groups of units such as marines and zealots. It is safer to use colossi against terrans rather than psionic storms, since ghosts counter high templar. Against zerg, colossi are very effective against hydralisks which have become more dangerous with roach support.
The beams do not have a "blind spot" and can strike enemies right next to the colossus.
Wings of Liberty
Legacy of the Void
In the single-player campaign, the colossus is one of three robotic siege units the player may use, the others being the reaver and wrathwalker. The colossus has the passive ability Fire Beam, which sets the ground hit by its attacks on fire, dealing 100 damage over 5 seconds to enemies nearby. This makes the colossus more potent than ever against masses of enemies. They deal heavy damage over time with this ability, in contrast to the reaver and wrathwalker having higher base damage but lower attack speed.
Increases the range of the colossus' attack from 6 to 9, giving it siege range.
Increases the armor of protoss ground units.
- +1 armor to shields per level.
- When colossi attack from a cliff, they can still be targeted by ranged units below them, unlike other ranged attackers such as the stalker.
- Air units have been noted to fly through colossi, their height being ignored by game mechanics in this sense. Blizzard does not intend to change this, as shrinking the air unit would look bad and shrinking the colossus would make its ability to walk up cliffs less believable.
- A purifier skin for the colossus will be available for those who purchase the collector's edition of Legacy of the Void.
- The Story so Far prelude of Legacy of the Void erroneously shows colossi being active during the Great War.