Stalker Void Ray Build (vs. Terran)
This build is centered on early aggression meant to contain and pressure with the use of fast Stalkers and air units, checking your opponent and giving you initiative in the match.
In opening, you should aim to pressure the Terran with your Stalkers by damaging his defending units or supply buildings and provoking his response, while microing to prevent your own units from taking substantial damage. Stalkers have a natural range advantage over Marines which can be abused even on the enemies ramp. A quick follow-up with Stargate units to give Stalkers vision of the high ground turns this early harass into an extremely deadly combination if the Terran fails to respond properly.
Basic Build Order
This build follows a modified 1 gate core opening
The sequence and timings of second Gate, Core, second Pylon are ideal and will finish together at the moment you can afford two Stalkers, but you must stop building probes at 15 to achieve this. This is the fastest known way to get two Stalkers on the field simultaneously.
It is useful in this build to scout the Terran taking gas with your initial probe scout, as 2 gas will indicate an early move into a higher tech range and will limit his Barracks unit count. The presence of multiple Barracks could indicate a strong early investment in early Marine mauraders, which will make your initial harass more difficult, and could negate it totally unless you have Void Rays. A fast Barracks and Tech Lab will normally indicate Reapers so if spotted a Stalker can remain at base to defend your mineral line until the threat is diffused. Your first two attacking Stalkers can further assess the unit count at your opponent's ramp. If his unit count is low he is likely teching up to exploit your vulnerabilities to Banshees, Ghosts, or quick Siege Tanks.
Upon building your first two Stalkers you should immediately press up into the Terran wall-in and begin harassing Marines, retreating once your shields are depleted, and then repeating this tactic once they recharge. If successful, this harass should be reinforced with an additional 2-4 Stalkers and possibly a Sentry if the Terran is massing Mauraders. It is not important to make kills, just to inflict damage and weaken the Terran force overall preventing him from breaking your contain. Marines should be targeted because they will be the only threat to your incoming air units and have lower life overall. Continue to pressure until your Void Ray arrives or until you are repelled.
Once the Stargate finishes, a Void Ray should be made, though an effective variation with Phoenixes is possible, Void Rays are often the default choice for their high damage output. Yours should be positioned at the Terran ramp to charge up on a Supply Depot before attacking Marines. This also provides your harassing Stalkers vision up the ramp to attack from safety due to their range advantage, and they should be used to deter any response by your opponent to attack your Void Ray. A second Void Ray can be added for additional pressure at the ramp if required, or can be sent to the opponent's mineral line to threaten your opponent's economy and split his defending forces.
With your first 2 probing Stalkers at your opponent's ramp you can then begin to make adaptive decisions on how best to continue your attack. A high Marine count that can repel your first Stalkers will grow quickly to overwhelm a Stalker/Void Ray contain so it is best to retreat and transition into higher tech, adding on Gateways and upgrades while mixing in Zealots and Sentries. A Bunker at the top of the Terran ramp is an efficient response to repel your first wave, but can immobilize the Terran and open him to exploitation through a two-pronged attack with Stalkers at your opponent's front, and a Void Ray at his mineral line. If the Terran is massing mauraders, accelerate the production of your Void Ray, cutting Stalkers or probes if necessary. If damage is done but your Void Ray and Stalker harass is rendered ineffective by growing Terran forces, Sentries can be added to forcefield the Terran ramp to block any aggression while you expand and scout him with an Observer or Hallucination
Short rush distances, lack of ramps: