Archons are beings of pure High Templar energy formed when two High Templars sacrifice themselves to create a powerful being. Archons can only attack, but they are also very strong. The majority of their health is actually their shield, which allows them to take a lot of damage, but retreat when needed and heal from a Shield Battery. Archons are introduced on the third campaign in StarCraft and are seen as very powerful being inside the campaign. However, they are fairly sluggish so they don't move as fast as Zealots do with the speed upgrade. However, there are High Templars in the game that cannot be made into Archons (Tassadar, being an example.)
 Game Usage
 Protoss vs Terran
Archons are rarely used against Terran. Due to the majority of its health being its shield, they absorb full damage from both Vultures and Tanks. Archons are generally only made when 2 High Templar have just depleted their energy on Storms.
 Protoss vs Zerg
When used with Zealots, Archons are powerful against Zerg. When fully upgraded, Archons kill Zerglings in a single hit, despite the Zerg's armor upgrades. This makes them important in the late-game when Zerglings with adrenal upgrade are mass produced.
 Protoss vs Protoss
Archons are effective against Zealot-heavy armies, as splash damage is very strong.