From Liquipedia Starcraft 2 Wiki
|Description||Powerful psionic attacker.|
|Cost||varies varies 12 4|
|Defense||10 350 0 (+1)|
The Archon is a powerful Protoss ranged unit, excellent in attacking biological enemy units and structures. An Archon is created when two of either Dark Templar or High Templar merge together on the battlefield: the Archon cannot be produced directly at any building. The Archon's attack can target either air or ground units and deals area-of-effect damage. The Archon also possesses a very high number of shield points, enabling it to withstand a great deal of punishment.
 Competitive Usage
Archons primarily function as support units. Because they have a range of 3, Archons can sit safely behind a line of Zealots and deal damage to the enemy forces without taking much damage. In addition, due to the increased shield regeneration rates in SC2, Archons are much more effective if they are pulled out of the battlefield before they die completely, as their shields will regenerate extremely quickly.
Archons can be moved while being merged by moving into them with units. Morphing Archons can be moved behind the army as protection, or taken to retreat with the rest of the army.
Archons are often used as part of or against a timing push. They serve as a player's quickest access to area of effect damage seeing as both the Colossi and High Templar with Psionic Storm require some time to become potent; for the former, the Robotic Support Bay needs to be built in addition to the Colossi itself, and for the latter, Psionic Storm needs to be researched and the High Templar needs to have gained enough energy for that tech path to be immediately useful.
Despite being a massive unit, archons are relatively easy to access early in the game. As such, they are particularly useful in PvP timing pushes due to their ability to crush Force Fields, as many players rely heavily on Force Fields for defense and would otherwise be extremely susceptible to timing pushes.
Archons are also merged when High Templar run out of energy in the field or if the opponent has detectors in play that render the Dark Templar ineffective.
The warp in cost of an Archon from two High Templar is 100/300, and the cost from two Dark Templar is 250/250. The cost of merging an archon from one of each is consequently 175/275. As gas is a more "precious" resource within StarCraft II, as it is used for teching and upgrades, it may be more favourable in some instances to warp in Dark Templar to be merged into Archons. However, the Protoss may elect to use High Templar in order to save more minerals for building chargelots, since chargelots are powerful units when paired with archons. This may be especially useful to follow a DT Fast Expand, as the saved gas allows for a faster transition into a more "standard" method of play.
 Vs. Protoss
Archons are strong against almost every Protoss unit, but most notably when up against Gateway units. Zealots are eaten up by splash and bonus damage while Stalkers will need up to 36 hits alone to kill an Archon. Sentries are rendered worthless due to an Archon's Massive attribute as they can break forcefields.
Saving Archons from near death and throwing them back into your army when their shields recharge can be a deciding factor in this match up, as very little economical gains in a mirror match can make or break a game.
One-on-one, an ideal counter for Archons in PvP is the Immortal, which will soak up damage with Hardened Shield. However, Immortals generally stay near the back of the army to avoid Zealots, and players generally won't attack Immortals with Archons anyway. This makes Immortals a softer counter in more normal mixed engagements. Other approaches to dealing with Archons effectively include catching Archons with little support with a flank or zealot surround, or focus firing them with groups of Colossi and/or Stalkers.
 Vs. Terran
After being harassed with Dark Templar a Terran player will place down Missile Turrets greatly limiting access to his base with cloaked units. To deal with this, leftover Dark Templar may be morphed into Archons and included in the main fighting force. As the current TvP playstyle favors Marine/Marauder use and both these units are subject to the Archon's bonus damage, the Archon can be a useful addition to the army. In addition, being a Massive unit makes them immune to being slowed by concussive shells. However care must be taken to avoid exposing Archons to direct fire from large groups.
 Vs. Zerg
Archons are very useful against Zerg, considering that their damage is significantly increased against biological targets. In fact, Archons can one-shot Zerglings and Banelings unless +1 carapace is researched. Conversely, this can be negated by the Protoss player researching additional tiers of Ground Weapons.
One viable build is Archon/Zealot, due to the fact that using High Templar for the Archons leads to heavy gas usage and an excess of minerals. Zealots act as meat shields and create a wall between the opponent's forces and the player's Archons, allowing them to strike from behind the Zealot wall without being in direct harm. This combination is extremely effective against armies composed of non-armored units, against which the Archons' damage bonus is most potent.
In addition, they are very powerful against Mutalisks, dealing a quarter of their health per hit to everything in the splash area. Since Mutalisks tend to clump, this can be devastating. But this also makes them susceptible to Psi Storm, and most players prefer High Templars for this reason.
Archons splash can also be used to kill Creep Tumors without detection. Two attacks on a friendly unit close enough to the tumor will kill it.
Archon's quotes (video and sound) - YouTube video.
 Patch Changes
|Patch 11 (version 0.13.0.15250)|
|Patch 14 (version 0.16.0.15580)|