Currently a lot of protoss players have problems with with a lategame Zerg, that techs to Broodlord/Infestor/spines. When going mass air this is not a problem at all.
The typical look of a game
The opening is a very delicate time. I usually build only one zealot adn completely skip warpgate tech and go for air upgrades instead. Thus it may be hard but not impossible to defend early attacks just with this zealot and building placement. Afterwards I build one Voidray and a phoenix and send them to the Third. Then I harass a bit, kill one or two queens and overlords and force 1-2 spores at each of his bases. Meanwhile I build a mothership and start building carriers and take my third. I build 5 cannons in its mineral line to deny zergling attacks (probe hold pos). You can sopport 5 stargate voidrays on 3 bases.
Around the 23 minute mark (Depending how agressive your opponent was you then can attack with a 3/3/3 upgraded toss Air army. But let us now look at things more specifically,
It starts with a forge-fast expand. The probe that places your first pylon should be send out to scout his pool timing and his expansions. So we get several cases:
6-7 pool: place a forge at the front, a plyon behind your mineral line and sacrifice the forge. This is basically how you have to play vs a 6- pool with forge Fe.
8-10 pool: Of course we have to go forge first. Now I would try to build the cannon in the front and stop worker production to get up your wall, Depending on the map, and your building placement, there you might have to pull probes to prevent him from entering your base.
Standard pool:[13-14]: Then i usually go nexus first. Go block his natural a bit with your probe. Don't loose that probe. I usually pull it away when its shields are down and scout again his main base. Look how many larvae he has when his pool a finishes and whether he took gas. If he has 3 larvae and he makes all of them at the moment when his pool finishes, it usually means that he will harass you a bit with lings. Sacrifice economony to complete your wall.
You really should scout whether he places his natural and his third.
At home your basic buildings will be Nexus forge, gateway, 3 Assimilators, Cybernetics Core and a Stargate. Against some early attacks it can be helpful to have a pylon on top of your ramp, so tht you can save the probes and build an emergency wall in up with 1-2 cannons behind it(usually such early attacks mean that he canceled his third; even if you loose some economy you are still OK, sometimes even loosing the natural is not a big problem)..
When the cybernetics core finishes I go for a stargate and 1-1 air upgrades cronoboosted, a voidray and a phoenix. and send them to his potential third. If your probescout him taking a gas you should send it over the way which a protential roach/ling attack would take, so that it can immediately turn around.
At home you should now I build my Fleet Beacon, a second stargate and 4-5 pylons. You should have 1-1 air upgrades as soon as the Fleet beacon finishes so that you can continue upgrading air attacks, your money is already quie high now, you can build a mothership(Chronobosst) and two carriers. A short time before it finishes, I take my third. I would place my rmy now on a cliff between the natural and the Third. At that time several things can happen:
Speedlings arrive: Cancel your third and really place it only when your mothership finishes.
A big roach attack : Due to your early void ray harass, it will usually never happen as early as usual; if it happens at the 13 minute mark it is still early. All your buildings are cloaked. Thus he either can immediately turn around, or he has to bring some Overseers with him. Depending on the number of overseers you can either snipe them, or just fight the roaches. One overseer means 2 less roaches, so if he has around 5 of them, his attack is already much smaller.
Hydras arrive: Carriers are really good against Hydras. It might look a bit scary, but just try to fosu some hydras down, if he starts focusing a Carrier pull tat one back, and if it might look as if he could snipe one of your Carriers you can use Vortex. this gives your shield time to regenerate and your Carriers time to replace lost interceptors. 2-1 Carriers are stronger than one might think.
If your third finishes place 5 cannons in the mineral line, add starports until you have 5 of them.
Mutalisks arrive. 3 cloaked carriers can easily take out 20 mutalisks. If it looks as if you mothership might go down just use a vortex. try to add cannons in all of your mineral lines and add the phoenix range. If he keeps going mutalisks, you can build some phoenixes, though it is most of the time not neccessary. he pretty much ran into a hard-counter.
Build up to 5 Carriers and then transisition into mass voidrays. For some time I always wanted to scout whether he goes for infestor/hydra/corruptor and adjust my composition correspondingly. However at some pouint I realized that 5 Carriers are the rioght number no matter what he does.
Usually at that times zergs will go for mass corruptors. Indeed Void-Rays are increbilily cost efficient versus corruptors, specially if they have better upgrades. But this indeed means that his ground army is weaker and that you can take more expansions. Just add 5 cannons to each mineral line and they are completely safe. Furthermore this means that he simply cannot counterattack, if you attack, because almost of his supply is in corruptors and drones.
Some timings/ a buildorder
9 Pylon 0:51, 15 Nexus 2:34, 16 Forge 2:59, 17 Pylon 3:14 , 18 Gateway 3:34, 19 Cannon 3:56, 20 Assimilator 4:11,22 Assimilator 4:27, 22 Assimilator 4:32, 22 Cybernetics Core 4:45, 28, 5:40 Stargate, 31 Air Weapons1(CB) 5:55
31 Pylon 5:55, 36: Void Ray(CB) 6:42, 39 Assimilator+Cannon 6:49, 40 6:59 Pylon, 45 Phoenix 7:24, 48 Fleet Beacon+Stargate+3 Pylons 7:45, 52 Air Armor (CB) 8:25, 62 Mothership (CB) 8:48, 64 Carrier 9:16, 72 9:51 Carrier
81 Air Weapons2(CB) 10:32, Nexus+ 2Pylons 10:43, 11:07 Carrier, 5 Cannons@3rd 11:45
12 Min: 61 Probes, 1 Void, 1 Phoenix, 1 Mothership, 2 Carrier, 7 Cannons
The attack/The late game:
The basic idea is now to attack and win the game. But of course, Life is not that simple.
I either fly my army to his main and kill his tech, so that I do not have face his bank. If the zerg lets this happen, it is basically over. Thus he has to fight earlier with his whole army. I am basically only afraid of a combinations of mass spores (around 30) Infestors and corruptors. His basic goal is to get increbily fungals. This can be quite hard If you do not see where my army is.
The best situation for him is when my carriers are clumped up and all the Interceptors move out at the same time and he catches all of them. But I never played against a zerg who could do that. Otherwise you should use your carriers to focus the infestors before they can throw of fungals. they still have a longer range. Sadly at my level most zergs just run infestors in and loose all of them.
When corruptors come you should move your carriers back a little bit and put the voidrays in front and just fight. You might use vortex on half of his army. Then he has to pull back and you get some bonus damage. If you know that he has now fungals left, and he moves all of his corruptors in the vortex, you can just move your void rays in, too.
After such final engagementy you might be down to 160 supply at most. Those 40 supply can easily be replenished quickly and he should run out of money much faster than you do. If you are over some (former) hatchery after such a fight and see a lot of eggs morphing, it might be worth to wait there. It might like 20 corruptors that you could pick up before they unite with those coming from the other hatcheries.
What beats this:
The early defense is really thin, a missed nydus worm on the minimap is pretty much game over. If the zerg plays really agressively wwith lings and than immediately builds 30 corruptors very early and he manages to catch yur air army when it is now over a bunch of cannons, you might have hard times. Continuously baneling busting your expansions can decrease you gas income so much, that you never reach your armysize.
If the zerg goes really early for double spire and mass upgrades, you might have hard times. But I basically think zerg cannot skip hydras after seeing 2 stargates.
So the goal uis to get a very gas heavy army with 9 upgrades. So your basic goal is to trade minerals for gas and kill of as much gas as possible. Cannons are a great late game unit since they do not cost supply. Void rays fight better versus corruptors the larger the numbers are, since they can change the target so quickly, i.e. it might happen that 20 corruptors shoot at the same void ray, although only 10 shots are needed to kill it. Furthermor it is much harder to use corruption effectively in large numbers.
Replay or it never happened
I uploaded some replays to my Drop.sc account. Since they all got renamed, here a short list of the content:
vs early pool
vs Baneling bust
vs early hydra attack (I played awfully, didnt place the stargate in time etc)