Fleet beacon

The fleet beacon is a protoss advanced building. Easily recognizable, the fleet beacon is built around a huge sphere carved from the largest and purest of khaydarin crystals. The beacon focuses psi through this sphere to strengthen and magnify the warp rift created by the stargate, allowing it to teleport the largest of protoss warships.

StarCraft
The fleet beacon provides upgrades to most protoss air units and gives access to the carrier.

Development
During the StarCraft alpha, the fleet beacon was known as the "warp accelerator."

StarCraft II
The fleet beacon plays a similar role in StarCraft II. It is a requirement for production of carriers and motherships.

Development
The flux vanes ability was removed in patch 1.2.

The fleet beacon used to research Apial Sensors (enhanced vision) and Gravitic Thrusters (enhanced speed) for the Phoenix. This has since been canceled.

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."

Heart of the Swarm Development
The tempest gained an upgrade called Quantic Reactor in Heart of the Swarm beta patch #6, researched at the fleet beacon. This upgrade costs 200 minerals and 200 vespene gas. It grants the tempest a +35 damage bonus against massive units. This was later removed.

These abilities were removed during the Heart of the Swarm beta.