From Liquipedia Starcraft 2 Wiki
Chrono Boost is the Protoss macro mechanic for StarCraft II. Located at the Nexus, this ability can be activated using 25 energy and is used to increase the production or research speed at the target building by 50%. This allows the building to do 30 seconds of work in 20 seconds, so production/research will complete 10 seconds earlier. This will work on any of your unit production buildings, as well as research buildings, creating interesting decision making scenarios where you must choose between opting for faster tech or faster unit production.
Chrono Boost also allows a building to regenerate shields quicker. Keep in mind that it does not allow shields to regenerate if building is under attack.
It is important to note that Chrono Boost also has the effect of reducing the warp-in cooldown time on Warpgates it is cast on.
While Chrono Boost cannot be used on an ally's buildings in a team game, if you control Zerg or Terran buildings they can also be Chrono Boosted. Zerg Cocoons cannot be Chrono Boosted. Chrono Boost will also have an effect on morphing buildings (such as Planetary Fortresses) and on the timer for Spawn Larva used by Queens.
 Competitive Usage
Against all three races, Chrono Boost is often used to hasten Probe production in order to have a stronger economy. Later, many Protoss players use Chrono Boost on upgrades from Technological structures as well as production structures such as Warpgates, Stargates and the Robotics Facility.
See some Chrono Boost Math for more technical details on Chrono Boost usage.
 Vs. Protoss
In the mirror match-up it is arguably most important to monitor the usage of Chrono Boost in the early game. Due to the significant amount of play based off of the Warpgate timing, scouting the use of Chrono Boost on the Cybernetics Core with your first Probe may be the only warning you can attain of an impending 4 Gate rush. The amount of stored chrono boost on a Nexus in PvP can also be the clue that it is being saved to chain chrono the warpgate tech research.
 Vs. Terran
With fast expand builds, chrono boost can be used to pump units out of a single gateway to gain just enough units to defend the pressure. See, for example, 1 gate FE, which uses a zealot and two stalkers chrono boosted out of a single gateway to defend the early nexus.
In the case of getting cloaked banshee detection in time to prevent damage, chrono boosting out the first observer or two observers helps.
 Vs. Zerg
Chronoboost may be used through the minimap. Zerg that mind control a probe and build a nexus can chronoboost any buildings they own. Chronoboost can be seen through the Fog of War (this is a bug apparently). You can not chronoboost your allies buildings though you could in the beta.
- A Terran building that is Chrono Boosted will fly faster.
- Chrono Boosting a Protoss building will make the shields regenerate faster (if building is currently regenerating shields), and Chrono Boosting a Zerg building will make it regenerate health faster.
 Patch Changes
|Patch 2 (version 0.4.0.14133)|