[G] TvZ BC Guide

Before the queen patch, I was working my way up the ladder playing mainly Mech in TvZ. You know, the usual Hellion FE did quite a bit damage back then.
Just as I got to diamond (or perhaps a bit before, I don't remember, since at that time I was mainly playing Tera), the Queen Patch came. When I came back to SC2, I found out suddenly Hellion openings are rubbish versus queens. I think there isn't a Terran player in the world who'd disagree the queen patch hurt that opening alot. Sure, you can deny a creep tumor or 2, but the damage doesn't nearly equals the cost of the amount of hellions you produce.

I tried to build an aggressive FE opening, targeted at doing damage near the 9:30 minute mark, where the queens are least relevant and Lair Tech hasn't kicked in yet. After a single game, I found a nice base strat, that has been refined into one of the two almost similar openings I always do in TvZ nowadays.

But then, I still tried to follow it up with Bio, or Mech. After around a dozen painful games, I understood that I really didn't like those styles. Bio required a ton of micro, and still felt a bit underwhelming ("split better!"), and Mech... it won sometimes, but I percived a few strategies just being too good vs Mech (Nydus and Drop Roachs, Mass Queen/Infestor/BL, and all that with combination of mass expand).

Finally, I tried to go for Mass BC late-game. And, to my surprise, it worked immensely well. Well, of course my first games with that strat were quite bad, and the zerg had a nice chances of killing me since I didn't do some basic (what I know now to be basic) things in order to prevent it. And they did kill me sometimes. If I made a single mistake, zerg would usually win the game straight away. But over time, I learned how to respond correctly, what to build, when to build it, and now, I finally got this guide ready for you.

So, lets get to the opening builds:
- 10 Supply Depot
- 12 Barracks(1)
- 13/14 Pull SCV from Barracks(1), make a 100hp Supply Depot to block scouting
- @100% Barracks OC, Marines, Put SCV on that 2nd depot.
- @100% Depot CC(2).
- @150 Minerals 2 Refineries (You can start each whenever you got 75 min).
- @200 minerals send an SCV to make a Barracks(2) on the natural entrance.
- 3 SCV's on each gas
- @100 Gas Factory, Tech Lab on Barracks(1).
- Start morphing finished CC into an OC.

Note:
You can do a 1 Rax FE without the 2nd Supply Depot, the build timings will not change much, but every second is good. You'll have to build the Refineries around 25 sec after the CC starts, delay your OC a bit, and build a 2nd supply depot soon anyway.


This is where there are 2 variations. I'll keep the Supply Depots out of the BO, but they are definitely very important, try to get supply blocked for as low time as possible.
Tank-Marine Variation
- 1 Refinary on Natural.
- Stimpack.
- @Factory100% Tech Lab, Starport.
- Tanks & Marines, might be 1 marauder in the end if you have the resources.
- @Tank(1) Siege Mode.
- @Starport100% Reactor.
- @Reactor 100% x2+x2 Medivacs (you might get find you have to delay other unit by 5 sec, for this, but Medivacs are your first priority).
- @400 Minerals CC(3), +1 Gas on Natural.
- 9:00~9:20 Flies out with 3 Tanks, Marines(, Marauders) inside 4 Medivacs (they fill perfectly).
- Engi Bay

*Notes:
1. You might want to squeeze in 1 hellion after the 1st tank, to clear the watchtower and make sure the Zerg is actually taking a 3rd.
2. You will not have resources to execute this to perfection - a total 5~10 sec loss is necessary, especially if you build a marauder.


Hellion-Marine-Marauder Variation
- Stimpack.
- Top Barracks produces Marauders, bottom barracks - Marines.
- @Factory100% Starport, 1 Hellion.
- @100 Hellion Reactor on Factory.
- Refinery (3) on Natural.
- @Starport100% Reactor.
- At this point, you'll be making 1 Marine. 1 Marauder and 2 Hellions. You'll not have enough minerals to continue this without stops, but that's ok. Just remember, Medivecs are highest priority.
- @Reactor 100% x2+x2 Medivacs
- @400 Minerals CC(3), +1 Gas on Natural.
- 9:20~9:40 Flies out with Marauders/Marines inside 4 Medivecs, Hellions rolling nearby or harassing the zerg 3rd (if you got the multitasking).
- Engi Bay

*Notes:
1. You should use your first hellion to take map control, and it would be a nice idea to send the rest with him to harass/scout the 3rd, unless zerg got roaches.
2. You will not have resources to execute this to perfection - you'll have even bigger resource gaps than in the 1st variation. Cut an SCV or 2, no more. You'll still end up about 10 supply more than the initial build, and with a better army overall.
3. If a WORSE opening in terms of direct follow up with BC's, since hellions and marauders are way worse at defending than Siege Tanks. You might have to research Siege and make new Tanks out of that factory, which will delay everything else a bit.
4. Is a safer opening against all-ins, and better damage (might even with the game).

This might be a small portion of time, but it's very important you do damage, and not lose all your army for nothing (or a few lings).

First, DO NOT GO FOR HIS MAIN! Not only that any good zerg will have overlords protecting the air pathes, but he'll usually be able to reinforce much faster to his main. The ONLY exception is on Shakuras, where you can put tanks on the lowground below his main and drop the rest of the army in. And that's only true with the tank opening!

On some maps, you Tal'Darim, you better drop bellow his 2nd due to the ground differance and the cute little choke there, and it's also possible on some other maps, but as a rule of thumb, you want to deny his 3rd.

If you went for tanks, once you kill his 3rd you pull back, and go into the next stage of the strategy.

If you went for the marauder hellion, you kill his 3rd (which, if it's already finished, means he has taken it too early to stop your push - he shouldn't be able to save it unless he has some amazing baneling hits, or has less workers than you - aka, has been making army for some time before he saw your push).
A tip here is to put your whole army on once control group, and the hellion-marines on the other - this helps you greatly at microing against banelings, moving all the light units while the healers and tanks stay 100% efficient. With enough micro you can focus the banelings with the marauders. This isn't relevant if he went pure ling or roaches, of course.
Once you think you did enough damage, pull back (unless the zerg was extremely greedy and took 4 bases, or was supply blocked somehow, and wasn't able to stop your push - than you just won).

And the most important thing - do not push if he hasn't been droning hard! (aka, if he attempred an all-in, 2 base pressure, or even 3-base roach/bling)

If you don't see a 3rd,(shame on you for not scouting, and also) don't attack! Defend, knowing that you got at least similar economy, while some zerg attack is comming. Also check for hidden expansion with a hellion, but that you need to do earlier anyway.

In case of earlier all-ins from the zerg, do not push. Also, don't make over 2 medivacs. If you hold his all-in without huge SCV losses, he's probably at the same eco as you, or worse. Just proceed to the next stage of the strat...

If you were busing pushing, you'll most likely get here with some large bank saved up. Don't worry, it's ok, improving your multitasking in this case is just optional (though could always help a bit).
If you held his all-in, you'll probably be able to spend minerals/gas and not let them pile up.

What you want to get, most likely at the same time, is the following:
- x2 Starport, switching the initial one with the Barracks' Tech-Lab.
- x2 Armory
(-If he went mutas, Turret the shit out of your main and Natural. Around 5 Turrets per expansion at least)
- @CC(4)
-Keep popping tanks in the meanwhile, get to around 5/6 total, place them in key positions to defend.
-When all the starports are ready, star building a Fusion core, and x2 Air Upgrades.
- When fusion core is ready, start making BC's. You should afford 3 BC's at a time on 3 Bases.

Mutas
Just making a note here, if he went for muta's, just Turrets are not enough. You'll also need to be making marines out of your barracks, 3 at a time. The second you land your 3rd, make Turrets there. Simply. you'll need the Turret Safe Islands (which I'll talk more about later) earlier, since he can make Curruptors earlier, since he'll see the BC's earlier.
If he continues making mutas past the first 10, you're in a slight problem, since this style is very quite hard to play against - but not impossible. Just make 2 Thors (if the map allows them to defend both the main and the natural, that's great), a few turrets behind each expansion, the marines at your 3rd, and the BC's protecting your tanks. More or less. This is gonna be hard, but if he didn't kill you by the time you got 6 BC/6 Raven, you're in a good spot.
Just remember to keep your main/natural protected by the Bio while the BC's fly to help secure a 4th.. that'll be later, though.

PF Baneling Bust
Zergs tend to do this really annoying thing. Luckily for you, it's actually way worse for them than it is for you. Doing this, they'll basically trade 35~40 Banelings for a PF and maby a few SCV's. That's 900~1000 Gas for 150 Gas, not to mention the minerals. Of course, it'd do huge damage if it delayed your mining. However, you should have 3 BC's, Tanks and some leftover Bio to clean the zerglings by than, and another orbital, ready to take the old PF's place. So, basically, he just fungalled his own knee doing that move.

Ground Attacks, 16:00ish
He will sometimes launch a 200/200 Ling/Ultra army at you. There are basically 2 possible scenarios here:
If you have only BC's, but enough to clear his whole army without losing your main (and the PF's you lose are replanishable with fresh CC's), you can just do that, and continue as normal. You can be sure that the secodn that happens he'll start morphing a billion Curruptors, though, so if you don't have the Turret Safe Islands yet, BUILD SOME.
If you alrady have something like 7 BC and 6 Raven, you might as well just lift up everthing, put all SCV's on Auto-Repair and move for his main. Kill the few fresh Curruptors he made there with 0 losses (will talk later about engagements), take out his Spire, his Hive, and procceed to go kill the rest of his bases, preferably scouting for a 2nd spire he must have put up while you were killing the Hive. Still, this is usually a once-sided race.

Ravens
This is your 2nd main unit in this match-up. In fact, without Ravens, BC's are absolutely nothing. They'll melt to curruptors with around 50% cost efficiency, which is not something you can nearly afford.
Your first 6 BC's are just defensive units, made to keep your base safe. The moment you got 6 BC's, mix in 6 more Ravens. Then, 3 BC's, and 14 more ravens. Your goals are basically:
1 - 3 BC
2 - 6 BC
3 - 6 BC 6 Raven
4 - 7 BC 8 Raven
5 - 7 BC 11 Raven
6 - 9 BC 12 Raven
- .. Many More Ravens
X - 9 BC 20 Ravens
X+ - More BC's.


Research
Don't forget to research all the BC upgrades, and Raven Energy+HSM, and optionally Turret/PF/PDD Range and Building Armor as well.
You can usually squeze in BC Energy before the first BC's, just don't forget to add Yomato right after. Raven Energy probably comes after that, HSM after that, and the rest are optional.
Your Air Attack gets the highest priority, since Armour doesn't change much vs Curruptors. Still, Armor has a higher priority than anything past the 4 main unit upgrades (though Armour 3 you might wait to get until you're maxed).


CC's
You'll have a ton of minerals banked up. You'll also need extra CC's in cases of Busts, and jsut to expand. After your CC(4), keep making CC's, either 1 or 2 at a time. You should have around 2 extra CC's ready for your next expansion, and 1 to either replace a baneling busted PF or just place as a static defense of the MAIN (this can really save you sometimes). But really, you'll have tons of banked minerals, so feel liberal with the amount of CC's you make. Watch the replays for reference.
After his first Push Attempts (or, once you hit benchmark 3 with no pushes from him), start taking the 4th. You might sometimes want to use CC(4) to reinforce the 3rd with a 2nd PF, that's not a bad choice.


Turret Safe Islands (TSI)
Basically, it goes by this principle - since the moment your opponent got Curruptors, there is no safe spot for your BC's, even inside your base - he can just flying and kill them. The ONLY way to make them safe, is to put up around 6~12 Turrets (depending on the stage of the game), making trade attempts very non-cost-efficient for the zergs (make that 0 efficiency the moment your ravens are out on the field with PDD energy).
You'll be making one of those the first time the oponent scouts your BC's. You'll usually make one near the 3rd, and sometimes a 2nd one on the high ground, if you fear a bust at the 3rd.
In the late-game, they'll have a very important roles as well, as they are what you need in order to progress your BC/Raven fleet.

Additional Starports
Around one starport per base (per 2 vespene geyser) until it's the late-game, which I'll talk about later.

Pure Corruptors
This is going to be something you commonly face.
First off, never engage this without energy. If you just used most of your Raven energy, just fly back to a Turret Safe Island til it recharges.
Another important thing, you need to snipe Curruptors from afar with Yamato Cannon. Each shot is 100 gas. The more you hit, the closer you are to winning the real war in this match-up, which is the Gas Efficiency War.
If they try to engage, you should also use PDD's to lower the damage to 0. If they don't go *inside* your BC cloud with curruptors, you can sometimes HSM them as well, but be aware - Curruptors move with the same speed as HSM's. If can send 3 Raven suicide squads into big Curruptor clouds though, and they will usually do terrible damage, with around 300%~600% gas efficiency (depending on how thick the cloud is, and how he splits).
But mainly, just Yoamto everything and use PDDs, than, if he keeps reinforcing or still has many Currutors when your PDD's are almost out of energy, retreat to the close TSI, an you basically traded a ton of energy for dozens of hundreds of gas. Energy recharges, gas doesn't.

Curruptor/Infestor
This is usually the most effective thing the Zerg can throw at you. If you're not microing spells well, or slack at the unit control, this has potential to even trade with 100% efficiency, which is the last thing you want. However, with decent level control you should still trade at around 250% gas efficiency, which is good enough.
Basically, keep most the Ravens a bit behind the BC's, throwing PDD's. Use EVERY Yomato on infestors. Keep a few ravens near the BC's, in case he uses NP on the BC's, use the HSM's on the immobile infestors. HSM will hit before he can make BC's yomato your own army. If your micro is really good, send single Ravens to flank his Infestors from the side, threatening HSM's. At the same time, you have the potential to HSM the curruptor could. The micro potential here is immense, just like with bio, only that the rewards are actually great instead of the "not completely losing" reward Bio has for micro.

Pure Infestor
You'll sometimes face this too. Yomato any infestor on sight, if they're burrowed, scan (or get 1 raven nearby).
You can also throw a raven from each of 2/3 sides, HSM'ng with the one who got close enough (one will by definition, since you'll close on them from all sides, they simply will have no choice but to get hit by a HSM fro mat least 1 side). While doing this, close in with the BC Fleet.
Also, you must never forget a few things:
1) Infested Terrans are just marines, even usually unupgraded. BC's tear through marines. Just remember to avenge hall damage with as many Yomato's into the infestors as you can.
2) Keep most ravens back from fungals, but keep a few to HSM infestors that decide to use NP.
3) Make a bit more BC's vs this.
4) Pure infestors suck. Scan, Yomato everything, get 40 points of hall damage, and kill off some unupgraded marines with BC's. That's it.

Nydus Worm
Some Zerg players will use Nydus quite aggressively. They'll usually try to put it inside your main, and sometime continuously use it for "hit and run" attacks.
If he you see such play, At the first wave, lift all the starports and clear it with the BC's. Then, immediately take 2 of your 4/5 tanks and set them on Patrol in the main. They should take the nydus out in around 6 seconds together, so you should be protected there. The rest of your expansions are at least dual PF's anyway, so you don't worry about zerglings there.
If he tries to do this with ultras, that this is most likely so late that your army is already something like 14+BC's, and 20+ Ravens. Just treat it as a usual 16 minute ling/ultra push, only that you have PF's everywhere. Just lift your production, fly it to the place protected by msot PF's, make a Fusion Core there, while flying your fleet to the enemy main. You should have full energy on everything, and if he made too many lings/Ultra's, and wont have more than 30 initial curruptors. By the time he remaxes on another 30, you'll probably not waste more than half the Raven energy (and around half the Yomato's, sadly) to kill the 30 Curruptors, and you'll make it to his base and take out his Hive/Spires, procceeding to hover around the map taking every hatchery. Even if he morphs every hatchery on the map into a Lair, it will still take another 100 seconds to make a Spire, which is 3 minutes total. If you split your army in 2, you should easily win that race, especially considering you got a ton of PF's, lots of lifted buildings, while he has.. a BC/Raven fleet killing every hatchery and spire on his half of the map, with 0 losses.

This is past the 4th base, when you got at least a bit less than benchmark X.
By this point, it should be over 30 minutes into the game, with Turret Islands in many places on your half of the map, and each player already owning most of his half (you are allowed to have 1 base less than him, but deny any attempt to grab a base in your half).

Basically, you creep the TSI's closer to your untaken expansions, and (once you secured them with large PF walls and Turrets filling the holes) to his last, and still mining expansions.
You'll probably have 6/7 starports, and something like 25 Ravens/16 BC's, with SCV's mostly mining gas and constructing Turrets/CC's.

Most important thing, DON'T MORPH MORE THAN 3 TOTAL OC'S! (Perferably just the first 2)
You only need them for scans - Mules will make you mine out minerals faster, but that doesn't give you any advantage, since you'll mine it out sooner or later anyway, and Mules can't mine gas. Just wasted scan energy. And you'll already have a two or three thousands of minerals floating despite the Turrets and PF's, at least.

http://drop.sc/225510
Most important replay. Showcases what happens if you hold the Zerg aggression, but don't build TSI's once he scouts the BC's.
For elaboration, this how you don't play, and that's why it's important to watch.

http://drop.sc/223507
A huge bust by the zerg at mid-game, which led to a base trade. As you see, Ravens efficiently keep your army at almost 0 losses, and he wasted most his gas on Bane/BL (he didn't scout the BC's). Not perfect, as I should have had a defensive PF at the front much earlier.

http://drop.sc/225511
Showcases how to play versus Zerg extreme aggression. My main mistakes were trying to get a 4th before my 3rd is dual PF, and not building a TSI the moment he saw my BC's. The 2nd one is because I only defined TSI's this game, understanding how important they are, and when exactly you need to use them.
Also, I didn't use Raven Suicide Squads well, since only after watching the replay, and most importantly, the last major fight, I realized how high the potential of splitting Ravens is. Still, the gas trade efficiency here was over 170% here even with terrible micro from me in that fight. That's a composition win, not mine, I admit. Well, and he also made some micro mistakes at 2 points, but that only put a nail in the coffin.

http://drop.sc/225509
Showcases some correct responses - start is similar to the 1st replay, but here I actually build a TSI, so his curruptors don't kill my BC's. The only mistake I think I did was not responding to the Nydus as I should have (patrolling marines or tanks, PF in the entrance to the main), but I only thought of that later. Apart from that, this game went pretty much as every game like this should. My 2nd mistake, in the ultra-late game, was moving away from a TSI with no energy. That's something you should never do - if you kill his army, let your energy recharge, while his gas wont.
Ignore slight BM near the end.

http://drop.sc/225508
Firs game, that I executed with everything I wrote here in the guide. This is where I added how to deal with Nydus. To be honest, had a huge embarrassing moment in this game - at one fight, I totally forgot the hotkey for HSM. I know this sounds a bit (a lot) awkward, but it just disappeared from my head before a fight, which cost me way heavier losses there than I should have. However, the zerg played an interesting style, required me to react to every his descision. Really good showcase to this strat, despite the BL's.
Here, the aggression for the zerg doesn't start before Broodlords, but

1. This doesn't seem of the highest level, I doubt it'll work
Try it, post replays of how it wasn't working, and than elaborate. Saying anything like this without testing is, at best, ignorance.

2.What's your win rate with this?
Well, I was testing and refining this build for a long time, and that was during the end of my semester.. so my winrate hasn't been 100%.
Still, I'm pretty sure that if you take away the all-ins I held, all ins that killed me, and when my attack killed him (I actually held and won around 70% of the all-ins), my win ratio was roughly 70%. Once I refined it, and got to the final build(s), it got to around 80% (think I played like 10 games, lost two in both of which he went mutas - not really good vs mutas still).

3.How hard is this to execute?
Naturally, if you expect to kill a Grandmaster with this, you'll need GM level micro and macro trough out the game. The first 10 minutes will require what they always do, especially if he goes for banes.
In the end, it'd come down to his Curruptor and Infestor splitting versus your Raven splitting. Still, if you're at his level, you should have the upper hand. Lets just say it's not harder than splitting a ton of marines, while the reward is definitly better than "trading meh-efficiently instead of losing all the army" - it's rather "kill most of his army for a few raven/bc/hall damage, instead of a ~1:1 trade".