Guide for Zerg Carapace Upgrades

vs Protoss

The Evolution Chamber.  It only costs 75 minerals and it lets us build Spore Crawlers!  But when should we start researching its time-consuming upgrades?

Well before we answer that question, let's look at some math (yay!):

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A zealot does 8 damage per blade.  After 3 hits, 48 damage kills a zergling (35 health).  Level  1 carapace upgrade adds 1 armor to the zergling, which means each blade of a zealot does only 7 damage.  However, 3 hits does 42 damage, which still kills the zergling.  The same applies to Level  2 carapace: A zergling will still fall in 3 hits to a zealot.  It's not until Level 3 carapace (3 armor), does a zealot's attack (5 damage per blade) take 4 shots in total to kill a zergling.

Henceforth, I'm going to leave the number crunching out of this Guide.

Stalkers are similar. They do 10 damage (post patch 6), which means it'll take 4 shots to kill a zergling. There is no change after Level 1 carapace.  It's not until Level 2 carapace, does it take 5 shots. 

Immortals (with their 20 damage), the Colossus (with their 20x2 damage), and Dark Templars(with their 45 damage) kill zerglings in two hits, one hit, and one hit respectively.  It's not until level 3 does this change only for the Immortal: taking 3 shots to kill a zergling.

Sentries do 8 damage, and would need to attack "5 times" (though continuous) to kill a zergling.  Interestingly enough, a Level 1 carapace upgrade gives the zergling enough armor to take 6 hits before dying.  Against archons (25 damage, but +10 against biological) would kill a zergling in one hit.  Getting the Level 1 carapace would at most leave the zergling with one extra HP (though dying in two hits is still pretty great, considering how fast lings attack and how slow the archon is).

So why should we bother early carapace upgrade? It seems to only make a difference for lings against sentries (how often does that even happen in the game right?).  Well before we start looking at the other Zerg units, let's look at what happens when the Protoss upgrades.  A zealot with a +1 attack upgrade will do 9 damage per blade, allowing it to kill a zergling in two hits.  Beginners should get into the habit of selecting their opponent's units whenever they engage in a battle, or scout, to see what the upgrades are at.  It is imperative to keep up in carapace upgrades, if the Protoss is going for +1 attack upgrades.  Now, it's become important to upgrade carapace not to have the advantage, but to keep up with your opponent's upgrades.

Evolving carapace isn't only for the zergling, though.  Let's look at the Queen.  I'm not going to show the math, but a +1 armor upgrade (from the Level  1 carapace upgrade) will allow the Queen to take more hits from every Protoss unit, except the Immortal (but it still takes ~10 shots), and the Archon (~6 shots).  Specifically, the upgrade makes the Queen even harder to kill by Phoenix rushes, which makes every Zerg happy.

I'm going to try and speed through these next parts:  The Roach benefits from the Level 1 Carapace Upgrade by being able to take two extra hits from a zealot before dying.  Stalkers, which get the attack bonus against armored, would only need one extra hit to kill a +1 armor Roach.  The Immortal, Dark Templar, and Colossus all kill the Roach in 4 hits, regardless of its +1 armor.  The Archon kills in 5 hits.  Generally speaking, the +1 armor greatly benefits the roach in combat against Zealots, Sentries, and Phoenix rushes. Remember this, when you next engage in battle with a Protoss.

The Hydralisk can take an extra hit from a Zealot (normally takes 6 hits to kill a Hydralisk) with its +1 armor.   Against Stalkers, Colossus and the Mothership, there is also benefit from the upgrade (one extra hit).   I'm not even going to bother talking about Sentries (but there is a huge benefit).   It's really only against the Immortal, Dark Templar, and Archon that there is no immediate benefit.

Lastly, and I guess most importantly: Banelings.  Honestly, its only against Zealots, Sentries and Stalkers does the +1 armor benefit: It allows the Banelings to take an additional hit before dying.  This of course, is great when rushing for those Banelings. 

I'm forgetting something aren't I?  Not really: The Ultralisk is such a great tank by itself, of course a +1 armor upgrade will show immediate benefit against all units.  This is indeed true, with the sole exception of the Dark Templar, that still kills with an unbelievable 14 shots!  The only Protoss unit that kills and Ultralisk faster is an Immortal: 13 shots.

So what's the point of knowing all this?  Well for starters, it shows there really is no reason to rush +1 carapace thinking that it'll help you win battles against the Protoss.  In fact, I would generally say the reason to get the Level 1 Carapace Upgrade (since all Zergs should always get this upgrade first) is to keep up with Protoss upgrades.  You do not want to fall behind when the Protoss army is getting their +1 attack.  I would generally suggest getting one evolution chamber for your +1 carapace (when you feel the Protoss army is going to get an upgrade soon).  The upgrade would be done in 140 seconds, or approximately 3.5 production cycles (assuming you are regularly injecting larva).  I would get my 2nd evolution chamber before the upgrade is done, so that I can dual research Level  1 attack and Level 2 carapace.  I'm not going to discuss the immediate benefits of Level 2 carapace.  Instead, consider this: The benefit from the Level 1 Carapace is balanced out by the +1 Protoss ground attack upgrade, but the same benefit is created once again when the Zerg has its Level 2 Carapace upgrade.  So bottom line, is always be ahead of upgrades than the Protoss.

I've highlighted some of the information I find is important in red, though I do suggest reading through all the material (I know it's heavy).  Useful information to note is how lings die to Zealots in 2 hits when you have no carapace upgrade, and the Protoss has +1 attack, as well as Roaches dying to Archons in 4 hits instead of 5, also when you have no carapace upgradee and the Protoss has +1.