Starcraft 2: Heart of the Swarm – Guide to Evolution Upgrades

Over the course of the single player campaign in Starcraft 2: Heart of the Swarm, you can evolve your units into more potent strains of themselves. Unlike the mutation upgrades, you don’t have the ability to change which strain you choose between levels. Once you settle on one, that’s it for the rest of the campaign.

However, once you beat the game, you unlock the Master Archives. You’ll be able to replay any mission you like to try to complete specific achievements and choose which strains you want to use. If a certain strain isn’t working out for you, you can switch it out for a different one which might help you better.


Raptor Strain – Leaps over obstacles and onto targets from range. Gains +2 damage, an increase of 40%. Can jump up and down cliffs.
Swarmling Strain – Spawns in groups of 3. Morphs almost instantly.

Recommendation: Raptors handsdown. The damage increase and the ability to traverse levels is huge. Raptors can also jump to units. If there’s front line units in the way, they can jump over them and get to the more vulnerable threats (like Siege Tanks).


Splitter Strain – Splits into two Baneling Spawns on death. Spawns deal less damage.
Hunter Strain – Leaps over obstacles and onto targets from long range. Can jump up and down cliffs.

Recommendation: Unlike the previous strain, I’d recommend Splitters on this one. When the Splitters explode the first time, they’ll follow up with mini-versions of themselves. I don’t often make Splitters throughout the campaign but when I come across fortified bases, I’ll generate the Splitter Banelings to help bust through and soften up targets.


Corpser Strain – Enemies damaged by the Roach will spawn two Roachlings if killed quickly.
Vile Strain – Attacks slow enemy movement and attack speeds by 75%. Heroic unit movement and attack speeds are slowed by 20%.

Recommendation: The Roach strains were a tossup. There are going to be times where you’re army will be engaging large hero units. Having the ability to apply the movement and attack speed debuff will greatly tilt the odds into your favor. Even a handful of these is enough to kite enemies around long enough without them being able to crush your army.


Impaler Strain – Morphs from Hydralisk. While burrowed, Impaler strikes at single targets with its piercing tentacle. Effective against armored enemies.
Lurker Strain – While burrowed, Lurker attacks multiple targets at once with its spines. Effective against light enemies.

Recommendation: Lurkers. I’ve loved using Lurkers since Starcraft: Brood War and it was nice to have these familiar guys. They never made a substantial contribution in my main army though. I usually keep the Hydralisks in their original form. Really though, the strain you choose is going to depend heavily on your play style. However, Impalers offer extra siege options instead of Swarm Hosts. So if you don’t want to rely on Locusts from Swarm Hosts to attack from afar, go for the Impalers.


Brood Lord Strain – Besieges ground targets from long range. Attacks spawn Broodlings.
Viper Strain – Pulls units to new locations. Enemies stunned for 1 second. Slows enemy ground units and prevents them from attacking. Drains life from allied units to restore energy. Attacks air units.

Recommendation: I leaned heavily towards the Brood Lords. Overall they’re a little easier to manage compared to Vipers. If you’re really good with your ability to micro and control your units, you may find Vipers to be a better selection for you. Having Brood Lords around does make it easier to soften up heavier ground targets from range before you move in your ground armies.

Swarm Host

Creeper – Generates creep while burrowed or rooted. Can travel quickly to any location with creep by using Deep Tunnel. Deep Tunnel cooldown: 10 seconds.
Carrion Strain – Spawns flying Locusts that can attack ground targets. Flying Locusts are faster and deal 50% more damage than ground Locusts but have 25% less life.

Recommendation: Carrion Strain all the way. Creeper strains do offer an element of mobility and the creep generation passive ability is a nice advantage for your units. But realistically, I haven’t much of a use for their Deep Tunnel abilities in the main campaign. The Carrion Strain offers more versatility. My army relied mainly on Hydralisks for anti-air but Carrion Strains offer another answer against units like Battlecruisers or Carriers.


Noxious Strain – Emits Noxious Cloud that deals 5 damage per second to enemy ground units. Toxic Blast deals 20 damage to enemy ground units and structures. Toxic Blast cooldown: 10 seconds
Torrasque Strain – Enters a Chrysalis when killed. After a short period, is reborn as a new Ultralisk. Rebirth cooldown: 60 seconds.

Recommendation: This one was a tough one. In my first play through, I went with Torrasque strains. Having a beefier and resilient army meant I could send these guys in first and follow up with my ranged units after. Their health allowed them to stick around much longer. If they die, they’d respawn a short time after and resume what they were doing. I’m going to try the Noxious strain in subsequent games. I have a feeling the extra splash damage from Noxious Cloud and Toxic Blast abilities will help with certain achievements that involve a timer.

Which strains did you end up picking on your first play through and why?

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1 Comment on Starcraft 2: Heart of the Swarm – Guide to Evolution Upgrades


On July 8, 2013 at 5:23 pm

I agree with you on most of your choices, but I would like to point out that the splitter strand baneling evolution’s spawns only deal 5 damage when they explode.

Also, could you include the unit strand upgrades that go best with the unit?