The fleet beacon used to research Apial Sensors (enhanced vision) and Gravitic Thrusters (enhanced speed) for the Phoenix[2]. This has since been canceled.[3]
During development of StarCraft II, the fleet beacon's form started off as a placeholder, though no adequate replacement was found for its structure. As such, its form was simply updated from its StarCraft appearance, though work was done on its sphere to make it look less like a "fishbowl."[4]
Heart of the Swarm Development[]
The following section contains information from a previous version of StarCraft II: Heart of the Swarm which is no longer valid.
The tempest gained an upgrade called Quantic Reactor in Heart of the Swarm beta patch #6, researched at the fleet beacon. This upgrade cost was 200 minerals and 200 vespene gas. It granted the tempest a +35 damage bonus against massive units[5]. This was later removed.[6]
↑Blizzard Entertainment staff. 2011-01-11. Patch 1.2.0 Now Live. Blizzard Entertainment. Accessed 2011-01-11.
↑Mielke, James. 2007-07-27. Protoss for a Day. 1up.com Accessed 2007-07-28.
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1) There is no observatory back in the game. You can warp in Observers at your Robotics Facility.
2) Observer's movement speed and Warp Prism's movement speed can be researched at Null Circuit. Phoenix has no upgrades for the movement speed and range at the current development stage.
3) Nullfier's Force Beam is its regular attack.
4) Hellion's upgrade can be researched at Armory.
Cydra. 2008-12-05. Protoss tech tree clarifications. Battle.net StarCraft II General Discussion Forum. Accessed 2008-12-05.