Game Guide: Protoss Pylon Support
Psi energy is the protoss form of supply, and it is drawn from a great psionic matrix that emanates from Aiur. While the nexus provides a link to said matrix, pylons are necessary to tap into it in order to provide power and psi to protoss settlements. Available psi is displayed in the upper right-hand corner of the main screen. Power is displayed as a circular, blue aura (also known as a power field) whenever you click on a pylon. No unit or structure can be warped-in outside these power fields.You can only warp-in structures or units on power fields.
When setting up a protoss base, make sure that key structures are powered by at least two or more pylons. This will make it more difficult for your opponent to shut down production or bring upgrades to a grinding halt by destroying the power source. If there's only one pylon supplying power to a structure, the enemy will have an easy time disabling it. Now, this doesn't mean you have to build pairs of pylons right next to each other, but try and keep your structures in the overlapped areas of pylon auras (these will be a brighter blue than the normal aura). Also, it is possible to warp-in certain tech units (dark templar, colossi, mothership) even if the prerequisite structures to build them (dark shrine, robotics bay, fleet beacon) are unpowered. Just make sure you have enough psi to support them, and that their respective production structures have power.
The protoss also have mobile power fields in the form of the warp prism. This vessel can travel to a location and go into phasing mode, which generates a power matrix like the pylon. Said matrix will allow you to build structures or warp-in units (provided you upgraded your gateways to warp gates).
