EPTI opened with one stargate for a scouting phoenix before 9:00 for the option to get range in time for mutas. Also, I made one void ray for a bit early game map control. I tried and sneak air +1/+1 in there ahead sometimes before base 4. I also opened with dual robo for the mass roach counter to stargate play. At base 4 or 5, excess minerals went into speed prisms to flank, and drop feedback infesters. (also of course to mineral dump into zealot drop harass)
I think the point of the tempest isn't to make a bunch of them and hope they kill a the zerg army of doom. I think their point is to control space for your void rays, to hold off infestors, to make incoming Corruptor pay a price for moving in, and allow for easier feedbacks. I sort of think of them as Protoss creep for the air.
Just like Zerg needs perfect injects for their macro to be a good race. I think Protoss needs perfect micro to work well. Stephano changed the game with how early he maxed out on roaches. I think the same can happen with Protoss micro. Miss an inject, and you're screwed. Miss a feed-back, and you're screwed. A few months or years isn't enough time to get good at anything. Compare a 2nd year piano student to a 10-20 year veteran musician.
Some people complain about Protoss being a gimmicky race. I prefer to think of them as precision micro dependent. Force-fields are gimmicky? When playing as non-protoss, you have to assume perfect force-fields are coming. If not, then you're taking an all-or-nothing risk. It's just another form of cheese. As Protoss, we have to take advantage of every trick we can to stay cost effective. Entomb all but one mineral patch then storm. Storm banked-up larva too for that matter. Be annoying any way you can, and be proud!
Sure, we have our easier to use robo based death ball. It's strong, slow, has timings related to it. But so does mech.
I think we've only just begun to see the promise of good protoss micro from LiquidHero and the like. I think they'll come a day when good (or gimmicky if you prefer to call it) protoss micro is just as essential as a good marine spilit, or a good roach flank.
