I've been practicing a lot of PvP recently and trying to step up my game and knowledge of the matchup while simultaneously getting plenty of information to put into my upcoming guide (Immortal/archon/chargelot). On the way, I've discovered a handful of tips, tricks, and general things to note that I think help to make my PvP significantly better, and I want to share them .
Proxy pylons
Especially once you get your natural saturated, you should constantly be building pylons along the edges of the map. This is pretty significant in all matchups, really. I think Protoss players should really start to work this into their macro and almost treat it like creep spread. It's pylon spread: you build a pylon and move your probe elsewhere, build a pylon and move your probe elsewhere, etc., etc., so that you're always building a proxy pylon along the edges of the map every 30 seconds. On larger maps like Whirlwind and Frost, this is super important in order to check for expansions and deal with them in a time-effective manner.
Scouting
In all matchups, but especially PvP, you need to be really aware of what your opponent is doing and where they are on the map. The opening of PvP is perhaps one of the most scouting-intensive processes in the game (of course, early game TvT is just as difficult). In the early game of PvP, you have to have your eyes peeled for proxies, units moving across the map, gas counts, expansion timings, etc., which can get really exhausting and difficult at times. On top of this, however, you have to be on top of mid game scouting too.
In order to scout properly in the mid game, you either need stargate units or blink stalkers constantly poking and scouting the composition and position of your opponent's army or you need to send hallucination scouts about once every minute. In particular, you're looking for the tech choice of your opponent, the gateway count, and the location and composition of your opponent's army.
If both players open with fairly passive macro openings, the most important times to scout are around 8:00-10:00, as this is when most 2-base attacks hit or specific tech goes down. Relative to your build, this is about the time when both players hit 2-base saturation. To simplify it: when your opponent reaches 2-base saturation, they are often committed to a certain tech path and/or gearing up for a 2-base timing.
Sidenote: placing those pylons helps out with map vision as well as using probes or stalkers to hold watchtowers. It's necessary to hold key positions like watchtowers so that you know if your opponent is moving out aggressively.
Playing Passively vs. Aggressively
If are ahead (you're natural goes down first and you stabilize), you want to play passively and keep on top of your scouting to make sure you get surprised by harassment or a mid game attack. In this way, you can slowly pull out the economic and tech lead and either 1) hit a really strong 2-base attack, or 2) get a safe 3rd base more quickly. The key here is to be scouting constantly: checking for your opponent's 3rd, army composition, and gateway count.
If you end up economically behind, you need to show some aggression in order to get even economically. This generally means aggressive tactics such as blink harass, DT drops, immortal drops, immortal pushes, and early gateway pushes, but even something as simple as walking to your opponent's base, forcing a nexus cannon and walking away can be an effective way to catch up. You don't necessarily have to do damage, you just have to step forward in some aggressive way and force a response.
A perfect example of this scenario is 1-gate FE (with robo) vs. a 2-gate FE (with robo). In this scenario, the 1-gate FE player should sit back, defend any aggression, and hold onto his economic lead while the 2-gate FE player needs to put on some pressure. When doing the 2-gate FE against a 1-gate FE, I often times just walk over with my initial units (4 stalkers/3 sentries/MSC) and force a photon overcharge, kill a few probes, possibly some sentries, then just walk home or recall.
Using Warp Prisms
When going immortal/archon/chargelot, warp prisms are very important for keeping your opponent pinned back with backstab pressure and/or things like immortal drops and DT drops. In addition, they also help you engage armies with specific tactics (the most common one being dropping 2 immortals on top of colossi and warping in a round of zealots).
One of the best ways to use the warp prism is to, (much like in PvT), always do a zealot drop whenever your opponent tries to move out. This is a surprisingly strong move that will bring you a high degree of success, especially in the later stages of the game.
These things NEED to survive and be microed well. Losing a warp prism, especially one loaded with units, can be disastrous and lead to a near-impossible situation to get out of. I suggest putting a lot of effort into using warp prisms well, especially if you're doing the immortal/archon/chargelot style. I think warp prisms and good warp prism control in this matchup are the hallmark of good macro play; you should always get a warp prism at some point if you plan to play a macro PvP.
Hopefully there's some good things to take from these notes!
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