2 Base Swarm Host + Spore ZvP
I want to share a ZvP build that I've been using for a couple of weeks now and that I think is very strong, especially against a rather passive FFE. I would like to encourage players better than me to try this out.
The idea behind this is to:
1. Use Spore Crawlers to make Swarm Hosts much harder to detect and thus increase their survivability drastically, making them almost unkillable.
2. Go with only two bases instead of three to hit when Protoss only has units that cannot deal with Locusts well.
It has already been observed that Swarm Hosts usually either roll an opponent with incredible cost efficiency or get overrun and die an expensive death. Since Locusts themselves do not cost anything, unit loss tab ratios of 1000 to 10000 in favour of Zerg become possible. On the other hand, once Protoss starts killing Swarm Hosts, Locust output often do not reach the critical mass anymore so that Zerg falls behind. One way to deal with this is to place your Hosts in a safe distance so you basically trade Locust lifetime for a lower risk of losing your Hosts. Blade55555 does it this way, as I understand it from his guide and his replays.
With this post, I would like to suggest a different way of dealing with the problem: combining Swarm Hosts with Spore Crawlers and laying siege on Protoss's base at a time when there are mostly only Gateway units out because these are really bad at dealing with Locusts. This requires us to go with only two bases--which sounds really all-innish from a WoL perspective because in that game Zerg has almost no way of harming a 2 base Protoss, often trades inefficiently against Force Fields and Immortals and thus has to get as much economy on three bases as possible. With Swarm Hosts in HotS, however, there is a possibility that the reasoning for exclusively playing ZvP on three quick bases just does not hold anymore; in that sense, we do not cut our base count because that is the only way to hit a timing, but because we do not necessarily NEED three bases. In fact, when I started experimenting with this composition, I only stayed on two bases because that is easier to manage when moving Overlords around and burrowing and unburrowing Spores and Swarm Hosts.
Hatchery at natural
2 Queens total
~3:45-4:00 1 gas @ 3:45-4:00, 2 workers
1st 100 gas: Lair
~5:45 take all gases, full saturation
next 100 gas: Overlord Speed
Ling Speed (can be skipped)
saturate 2 bases, at least 20 drones at the natural
Infestation Pit when Lair finishes
Explanation and Basic Execution
This is just a general outline of getting out Swarm Hosts quickly while saturating two bases. The opening is a standard Pool first, with the only difference being that you cannot take your third if Protoss delays your natural too much. Hence, I prefer 12 or 14 Pool over 15 Pool to get Lings out quicker if needed. As a gas timing, I like something around 3:45 to 4:00 because that way you can start mining gas just when you else would reach oversaturation if you natural is delayed. There is generally no pressure to get an an ultra-fast Lair because an Infestation Pit builds quickly and Swarm Hosts cost a lot of money so you have to saturate your mineral lines first anyway. You shouldn't go later than 6:00 though because of early Gateway all-ins.
The next important component is Overlord Speed. Make sure you have this ready when Swarm Hosts are out. Blizzard recently moved Overlord Speed from Lair to Hatchery, but this does not really affect us because we go for a quick Lair anyway. You can still research it with the first 100 gas after starting your Lair because it eases scouting enormously. Ling Speed is not mandatory since you do not need to make Lings in any case.
Once your Lair has finished, build an Infestation Pit and start making Swarm Hosts. The Locust upgrade (increases lifetime of Locusts from 15 to 25) is absolutely worth it in almost any case because it eliminates the 10-second downtime between Locust waves and increases Swarm Hosts' range massively: if you attack an unguarded third base of Protoss from a travel distance of 10 seconds, every Locust wave attacks three times longer. That is a lot given that e.g. 10 Swarm Hosts worth of Locusts do 279 dps!
Once your first two or three Swarm Hosts are out, take most of your Overlords, three to four Drones and the Swarm Hosts to a more-or-less hidden spot outside of the Protoss base. Spit creep there and make your Drones into Spore Crawlers. Rally in more Swarm Hosts, make a creep road towards Protoss and move the Spores as close to the base as possible. Then burrow the Swarm Hosts just behind the Spores and rally the Locusts in. From now on all you have to do is reinforce with more Swarm Hosts and bring more Drones to replace killed Spores. Make sure that Locusts are always firing at something, preferably buildings because these cannot run away. The easiest way to do this is to rally the Swarm Hosts on an important building and then shift-rally on some space behind the building. That way, Locusts will kill that building first, and then continue with a-moving to that second spot. You can also move-shot Locusts towards a building to increase the number of Locusts firing. In general, though, you should have at least 10 Swarm Hosts or so for it to be worth it having Locusts firing at buildings with Protoss Units shooting at them.
This is what your setup should look like. Observers cannot come close enough to detect Swarm Hosts. They can go around, of course, but you can also place Spores all around your Swarm Hosts because they are cheap.
I usually add all Overlords, Drones, and Spores used offensively to one control group so that I can move them to one specific location quickly if I have to. Swarm Hosts go to another control group. I think the most important thing is to use the Swarm Host's rally hotkey instead of right-clicking so you do not accidentally suicide newly made Hosts into the opponent's base. What also happens regularly is that I accidentally burrow Swarm Hosts somewhere on the map because I have added these to the control group as eggs and then burrowed them all. To avoid this, when burrowing you should use Ctrl-click to only select the Hosts at the front. In that case, you can also use right-click to rally.
In general, moving Overlords, Spores, and everything around takes a while to get used to because they are handled very differently from what Zerg normally uses. But it certainly is not overly difficult, either.
On another note, upgrades do not seem to be extremely important with Swarm Hosts with Locusts doing enormous damage anyway. I normally get +1 Carapace, though, since it helps them to close in on the opponent and, of course, affects all other ground units.
Protoss Reaction and Reacting to Protoss
Scout Protoss with an Overlord at a usual timing, i.e. something between 7:00 and 8:00. Overlord Speed should finish around the same time and also allow to delay the scout a bit. The nice thing is that with Overlord Speed you should be able to see everything with ease.
If you see a Stargate, you need extra Spores, both with your Swarm Hosts and at home. I usually make two per base and at least double the amount the number of Spores I make offensively since the new Void Ray is relatively good against Spores. You have to replace the Drones immediately, of course. If I see a Robo, I make a round of Speedlings or two because Robo armies can break Locust waves early on. In that case, it is good to have a few units that can fill the gap and save the Swarm Hosts' day.
Once your Spores and Swarm Hosts are in position, most Protoss players react with a Stargate, and then usually with Void Rays (Phoenixes and Oracles run out of energy, Tempests have too low dps, and Carriers take too long to get out). In that case, I usually add some Hydras so that Void Rays are forced to kill the Hydras first in case my Swarm Hosts are without protection. Also, Protoss can pick off reinforcing Swarm Hosts with air units.
Colossi are very good at killing Locusts, too. In fact, they are the only ground unit that can harm a big Swarm Host army in the long run. Once I see my opponent taking that route, I start Hive to get some Vipers out because Abduct is simply extremely good if you pull Colossi into Locust waves. In conjunction with Swarm Hosts, I think they are much more effective than Corruptors, and at the same time more versatile. But in the long run, replacing Spores with the more standard Corruptors and Overseers is reasonable, too. That way of deflecting detection is much more expensive, but also allows you to move around more quickly with your Swarm Hosts.
If you do not see much of an reaction in tech terms, or Protoss does not fight your Locust waves at all, your opponent most likely tries to trade bases. In that case, you only have to defend your natural (or even main) to win since "free" Locusts are way powerful in a base trade scenario. Admittedly, I have not played against people who do this very much, but you react similarly as in any other ZvP base trade: make a lot of Spines in a position to which you think the opponent will not get in time and rally all new units behind that. With Swarm Hosts you can also make Spores since that, again, effectively forces Protoss to kill those first. The same things you should do if you feel you are getting ahead. You don't want to lose against some surprise DTs, obviously.
If Protoss goes for an Immortal/Sentry all-in you have to play more defensively because he already has two or three Immortals at the time you are trying to set up the contain. I have not encountered this build very much recently (probably because of the success that Skytoss has at the moment), but since Blade has already shown with his post that Swarm Hosts can defend it quite easily on three bases, defending it on two should not be much of a problem. Once you have enough Hosts to keep the Immortal/Sentry ball in check, you should be able to move out and at least pressure Protoss if he tries to take a third base. But I don't want to speculate too much.
If Protoss one-bases (which has only happened to me once), you should probably abandon Swarm Hosts and focus defending until he expands.
I have intentionally not mententioned any third base timing so far because I do not feel confident enough to give a rule for this. Of course, you can expand if Protoss falls behind against your Swarm Host attack, and I usually do.
The good thing about this build is that you, compared to drop and Nydus strategies, do not have to invest much into any tech. Infestation Pit and Overlord Speed are only 100/100 each and have other uses. You also do not rely on hiding a lot. The worst thing that can happen is that Protoss manages to catch your Drones before they become Spores. That happening is not very likely, though, because a scouting Protoss will know that you have not taken an early third base and play rather defensively.
Edit: Since beta replays cannot be watched any more, I uploaded more recent ones. I refined the strategy a bit, but in its core, it is still the same thing.
Blade's Swarm Host play
Tips and infos on Swarm Hosts by Existor
I'm not good, and by these forums' standards I am probably really bad (at least made it to low masters in Wings for two seasons last year). But I wanted to share this, not because it is giving me a lot of success (and Protoss rage), but because I haven't seen anyone really try this. So I decided it was better to make this post than not to!
Also, feel free to PM me for practice games and such, and I'll give you my character code!
TL;DR: Bring Spores with your Swarm Hosts and they won't die (the latter).