Starcraft 2 Heart of the Swarm Campaign Only Units List Guide

Starcraft 2 Campaign Guide --> Heart of the Swarm Campaign Guide --> HotS Campaign Units (you are here)

There are many Zerg units in the Heart of the Swarm campaign that are completely different from the units you encounter in multiplayer. There are also a handful of new campaign-only units (and even more variations of old units) which are only available for use in the Heart the Swarm.

The introduction of these campaign-only units is a very welcome decision by Blizzard as it allowed the developers to introduce a lot of new and unique strategies for players to use in the campaign without ruining the balance of the multiplayer competitive game. It allowed the developers to complete and balance the campaign missions as well before the release of the expansion without the need for an extensive beta test like they used to balance the multiplayer version of Heart of the Swarm.

This guide is for the single player campaign-only units, evolutions, and upgrades. It does not go over the new multiplayer units and changes to old multiplayer units. If you are interested in the new units available in competitive play in Heart of the Swarm check out our page on New Units in Heart of the Swarm. If you are interested in how old units, upgrades and structures have changed in competitive play, see our Starcraft 2 Heart of the Swarm Changes Overview.

Below, you will find a full list of Zerg units that you can use in the Heart of the Swarm campaign. Since all of the units are slightly different in the campaign versus in the live multiplayer version of the game, every Zerg unit will be listed. For example, the base Zergling in the Heart of the Swarm campaign is the same as the Zergling from the multiplayer version Campaign-only units will be marked with a Campaign Only tag.

Quick links to each unit:

Zergling
Swarm Queen
Roach
Baneling
Abomination
Hydralisk
Lurker
Impaler
Mutalisk
Brood Lord
Viper
Ultralisk
Infestor
Swarm Host

Zergling - HotS Campaign Unit

Stats Before Mutations or Evolutions:

Cost: 1 supply, 50 minerals (Zerglings hatch 2 at a time for this cost)
Build Time: 24 seconds
Requires: Spawning Pool
Class: Light, Biological
Health: 35
Armor: 0
Movement Speed: 2.95 (+.88 on creep) 
Primary Ground Attack: 5 (+1 per upgrade) damage. .7 attack speed. Melee range.
Primary Air Attack: None.

Zergling Mutations

• Hardened Carapace: +10 Zergling life.
• Adrenal Overload: Attack speed increased by 50%.
• Metabolic Boost: Movement speed increased by 60%.

Zergling Evolutions

• Raptor: Zerglings can leap over obstacles, jumping to their target. Raptor Zerglings can also jump up and down cliffs. +2 damage to base attack.

• Swarmling: Zerglings spawn in groups of 3 instead of 2. Zerglings production time reduced to 2 seconds.

As you might expect, the Zergling is one of the core units in the Zerg army in Heart of the Swarm. The default Zergling is just like the Zergling from the multiplayer version. However, there are no upgrades available at the Spawning Pool in the campaign. Instead, permanent upgrades to the Zergling are available at the Evolution Pit.

Swarm Queen - HotS Campaign Unit

Stats Before Mutations or Evolutions:

Cost: 2 supplies, 150 minerals, and 50 vespene gas.
Build Time: 30 seconds
Requires: Spawning Pool
Class: Armored, Biological, and Psionic
Health: 150 Health
Energy: 200 max.
Armor: 1
Movement Speed: 2.25 (+.5 on Creep)
Primary Ground Attack: 4 (+1) damage. 6 (+1) damage versus armored. Two attacks. 1.0 attack speed. Range of 5.
Primary Air Attack: 9 (+1) damage. 1.0 attack speed. Range of 7.

Abilities

• Spawn Creep Tumor: 15 second cooldown. Spawns a Creep Tumor on the map. Creep tumors burrow 2-3x faster in the campaign than they do in multiplayer. Creep Tumors also cost no energy in the campaign. Creep Tumors may spawn other Creep Tumors after surviving for 15 seconds. Once a Creep Tumor successfully generates a new Creep Tumor, it can no longer make new Creep Tumors, although the new one can. If the new Creep Tumor is killed off before it can burrow, the original Creep Tumor retains its ability to generate a Creep Tumor in the campaign. In live, a Creep Tumor can only create 1 new Creep Tumor regardless of whether the new is able to burrow or not. To simplify: Creep Tumors are better and easier to spread in the campaign.

• Rapid Transfusion: Costs 10 energy, 3 second cooldown. Heals a target or structure for 25 life over time. This effect seems to occur over about 3 seconds. Instead of Transfuse, Queens in the HotS campaign possess the "Rapid Transfusion" ability. This ability will auto-cast by default.

There are no Swarm Queen mutations or evolutions.

In the Heart of the Swarm campaign, Queens are quite different than they are in the live version. First off, they are more expensive, actually costing vespene gas in the campaign. However, they are also much better. Spawn Creep Tumor costs no energy, and creep tumors are better in the campaign than they are in live.

Queens do have less health in the campaign (150 versus 175 in live), but they make up for this with their Rapid Transfusion skill. While Transfusion (the live version) and Rapid Transfusion (the campaign version) both restore 2.5 health per energy point spent, Rapid Transfusion will automatically cast and costs less energy, making it useful as an army-wide healing skill. Queens also do bonus damage to armored ground units (an extra 4 DPS) and move much faster off creep than Queens in the multiplayer game.

Roach - HotS Campaign Unit

Stats Before Mutations or Evolutions:

Cost: 2 supplies, 75 minerals, 25 vespene gas.
Build Time: 27 seconds
Requires: Roach
Class: Armored, Biological
Health: 120 Health
Armor: 1.
Movement Speed: 2.25 (+.67 on creep)
Primary Ground Attack: 16 (+2) damage. 2 attack speed. Range of 4.
Primary Air Attack: None.

Roach Mutations

• Hydriodic Bile: Roaches deal a bonus +8 damage to light units.
• Adaptive Plating: Roaches gain +3 armor when under 50% health. 
• Tunneling Claws: Roaches can move at full speed while burrowed. Life regeneration rate while burrowed increased by 100%.

Roach Evolutions

• Corpser: Enemies will spawn 2 Roachlings upon death if they die within a few seconds of being attacked by a Corpser Roach.

• Vile: Attack and movement speed of enemy units is reduced by 75% for several seconds after being attacked by a Vile Roach. This is only a 20% reduction for hero units.

The Heart of the Swarm campaign Roach is much different than the multiplayer version of the Roach, and possibly not for the better. In the campaign, it has 25 less HP by default and loses access to its movement speed upgrade at the Roach Warren. The evolutions help boost the Roach's strength, but its low HP makes it relatively fragile in the campaign missions. The problem is there are just way too many Siege Tanks and air units for a low HP Roach to be a major part of your army.

Baneling - HotS Campaign Unit

Stats Before Mutations or Evolutions:

Cost: 1 Zergling (25 minerals, 1/2 a supply), 25 minerals, 15 vespene gas.
Build Time: 10 seconds. Banelings are morphed from Zerglings rather than Larva.
Requires: Baneling Nest
Class: Biological
Health: 30.
Armor: 0
Movement Speed: 2.95 (+.88 on creep).
Primary Ground Attack: 40 (+4) damage to targets within the blast radius, 80 (+5)damage if that is a structure. Banelings explode .2 seconds of coming in melee range of their target, sacrificing the unit and dealing splash damage. Banelings that die from damage also explode, dealing splash damage to all targets within range.
Primary Air Attack: None.

Baneling Mutations

• Corrosive Acid: Damage dealt to primary target is increased by 100%. Splash damage remains unchanged.
• Rupture: Blast radius increased by 50%.
• Regenerative Acid:  In addition to dealing damage, Baneling explosions heal nearby enemy units and structures.

Baneling Evolutions

• Splitter: Splitter Banelings turn into 2 Baneling Spawn upon death. Splitter Banelings do full damage upon death in addition to forming these 2 Baneling Spawn. Baneling Spawn have 20 health (instead of 30 of a full Baneling) and only deal 5 damage in their explosion (10 to structures).

• Hunter: Hunter Banelings can leap up and down cliffs and will jump to their targets.

Initially, the Baneling in the Heart of the Swarm campaign functions very similarly to the Baneling in the live version of Starcraft 2. In the end though, the campaign Baneling is much better. The campaign Baneling always moves as fast as if it had the Centrifugal Hooks upgrade. Additionally, the mutations and evolutions significantly improve the strength of the Baneling.

Aberration - HotS Campaign Unit - Campaign Only

Stats Before Mutations or Evolutions:

Cost: 3 supplies, 200 minerals, 75 vespene gas.
Build Time: 30 seconds
Requires: Evolution Chamber
Class: Armored, Biological, and Massive
Health: 275 health.
Armor: 2.
Movement Speed: 2.95 (+.88 on creep)
Primary Ground Attack: 20 (+2) versus unarmored, 40 (+3) versus armored). 1.2 weapon speed. Melee range.
Primary Air Attack: None.

There are no Aberration evolutions or mutations.

The Aberration is an amazing unit and very underrated. I think a lot of players accidentally overlook this unit because it does not have any evolutions or mutations and is unique to the campaign when in reality this unit is extremely good.

One thing that makes this unit so good is that it is the only Zerg unit that will walk over smaller ground units. In other words, both Zerglings and Aberrations can occupy the same spot on the ground and attack the same target. The Aberration can walk right over top of all Zerg ground units except Ultralisks without having to "push" them out of the way. This means that they  never get caught in the back in a big fight. For example, if you are using a Hydralisk, Queen and Ultralisk army, it is easy to let your Ultralisks to get stuck behind your Hydralisks and Queens, causing the Ultralisks to not participate in the fight. Abberations on the other hand can walk right over the Hydralisks and join the battle right away.

Additionally, the Aberration's stats are just really good. Their 40 base damage to armored (49 with 3 upgrades) is huge, and it lets them shred buildings and heavy Terran fortifications in seconds. 40 damage per swipe is huge on a 3 supply unit. With a 1.2 attack speed, this is a DPS against armored units of 33.33. Compare that to the Ultralisk, which despite costing 6 supplies instead of 3 supplies, has a DPS of 25. Supply for supply, the Aberration does about double the damage of an Ultralisk versus armored units!

Hydralisk - HotS Campaign Unit

Stats Before Mutations or Evolutions:

Cost: 2 supplies, 100 minerals, 50 vespene gas.
Build Time: 30 seconds
Requires: Hydralisk Den
Class: Light, Biological
Health: 80 Health
Armor: 0.
Movement Speed: 2.25 (+.67 on creep)
Primary Ground Attack: 12 (+1) damage. .83 attack speed. Range of 5.
Primary Air Attack: 12 (+1) damage. .83 attack speed. Range of 5.

Hydralisk Mutations

• Frenzy: Gives the Hydralisk the "Frenzy" ability. This is a free to use skill with a 30 second cooldown that increases the Hydralisk's attack speed by 50% for 15 seconds.  
• Ancillary Carapace: Gives the Hydralisk +20 life. 
• Grooved Spines: Increases the range of the Hydralisk's attacks from 5 to 6.

Hydralisks Evolutions

• Lurker: The Lurker evolution grants the Hydralisk the ability to morph into a Lurker. The Lurker is a separate unit from the Hydralisk and does not replace the Hydralisk.

• Impaler: The Impaler evolution grants the Hydralisk the ability to morph into an Impaler. The Impaler is a separate unit from the Hydralisk and does not replace it.

The Hydralisk is a balanced unit that can hit both ground and air units from range. It has relatively high DPS for a ranged unit but also has rather low HP. The Ancillary Carapace upgrade improves the Hydralisk's survivability significantly.

Lurker - HotS Campaign Unit - Campaign Only

Stats Before Mutations or Evolutions:

Cost: 3 supplies (total), 50 minerals, 100 vespene gas, 1 Hydralisk (the Lurker is evolved from the Hydralisk).
Build Time: 15 seconds.
Requires: Lurker Den (Morphed from the Hydralisk den for 100 minerals and 50 vespene.
Class: Armored, Biological
Health: 200 health.
Armor: 1.
Movement Speed: 3.38 (+1.01 on creep)
Primary Ground Attack: 20 (+2) damage versus regular, 30 (+3) damage versus light. 1.45 attack speed. Range of 6.
Primary Air Attack: None.

There are no Lurker mutation strains available. The Lurker is an evolution of the Hydralisk.

The Lurker, like the Impaler, is a high-damage evolution of the Hydralisk that can only attack while burrowed and can only attack ground units. The Lurker is extremely fast and has a moderate range of 6. Its attack does full damage to all units within its rather generous area of effect.

The Lurker is fast, but its short range and need to burrow make it a micro-intense unit if used on offense. It is an effective defensive unit.

Impaler - HotS Campaign Unit - Campaign Only

Stats Before Mutations or Evolutions:

Cost: 3 supplies (total), 1 Hydralisk, 50 minerals, 100 vespene gas. Impalers evolve from Hydralisks.
Build Time: 15 seconds
Requires: Impaler Den (Mutated from Hydralisk Den for 100 minerals and 50 vespene).
Class: Armored, Biological
Health: 200 Health.
Armor: 1
Movement Speed: 2.75 (+.82 on creep)
Primary Ground Attack: 20 (+2) damage versus regular. 45 (+4) damage versus armored. 1.45 attack speed. Range of 11.
Primary Air Attack: None.

There are no Impaler mutations strains. The Impaler is an evolution option of the Hydralisk.

The Impaler is an excellent unit that can be evolved from the Hydralisk once you complete the Hydralisk evolution mission. While it can only attack while burrowed, it has a long enough range that it can be used on both offense and defense. It does massive amounts of DPS to armored units, particularly given its range. Since buildings count as armored units, it is very effective at attacking enemy structures as well. It is a very cost effective unit as well if microed properly.

Mutalisk - HotS Campaign Unit

Stats Before Mutations or Evolutions:

Cost: 2 supplies, 100 minerals, 100 vespene gas.
Build Time: 33 seconds
Requires: Spire
Class: Light, Biological
Health: 120 health
Armor: 0
Movement Speed: 3.75
Primary Ground Attack: 9 (+1) damage. 1.52 attack speed. Range of 3. Bounces up to 3 times to nearby targets, dealing reduced damage with each bounce.
Primary Air Attack: 9 (+1) damage. 1.52 attack speed. Range of 3. Bounces up to 3 times to nearby targets, dealing reduced damage with each bounce.

Mutalisk Mutations

• Vicious Glave: Mutalisks attacks bounce three more times, hitting up to six targets.
• Rapid Regeneration: Mutalisks regenerate 10 life per second while out of combat. Must remain out of combat for 5 seconds before this kicks in.
• Sundering Glave: Mutalisks gain +9 () damage versus armored targets. Attacks no longer bounce to additional targets.

Mutalisk Evolutions

• Brood Lord: The Brood Lord can be morphed from the Mutalisks if this evolution is selected. The Brood Lord does not take away the option of making Mutalisks, you can use both Mutalisks and Brood Lords in the same mission. The Brood Lord is discussed in its own section below.

• Viper: The Viper can be morphed from the Mutalisk if this evolution is selected. The Viper does not take away the option of making Mutalisks, you can use both Vipers and Mutalisks in the same mission. The Viper is in its own section below.

The default Mutalisk is a bit weaker in the Heart of the Swarm campaign than it is in the live version of the game. It is a little bit slower in the campaign and does not have its default regeneration that it does in the live version of the multiplayer. It can get regeneration abilities through the mutations, but this regeneration is not as strong as the multiplayer version since it takes 5 seconds to kick in.

The redeeming quality of the Mutalisks is that in the first few missions that they are introduced, there is a very limited amount of anti-air units available. With no anti-air around, Mutalisks are naturally very strong.

Mutalisks are also good units to use in later missions on defense when you need to defend multiple locations. With the Sundering Glave evolution, the Mutalisk can deal a solid amount of bonus damage to small armored incursions that otherwise can be very devastating, such as a pack of 2-3 Thors and 6 Siege Tanks.

On offense, they lose their luster in the later missions, especially versus the Terran computer. Too many Thors, Missile Turrets, and Marines.

Brood Lord - HotS Campaign Unit

Stats Before Mutations or Evolutions:

Cost: 4 supplies (total), 150 minerals, 150 vespene gas, 1 Mutalisk (Brood Lords evolve from Mutalisks)
Build Time: 15 seconds
Requires: Greater Spire
Class: Armored, Biological, Massive
Health: 225 Health
Armor: 1.
Movement Speed: 1.88
Primary Ground Attack: 20 (+2) damage. 2.5 attack speed. Range of 9.5.
Primary Air Attack: None

There are no Brood Lord evolution strains. The Brood Lord is an evolution of the Mutalisk. In the campaign, Brood Lords evolve from Mutalisks, as there are no Corruptors in the campaign.

Each time a Brood Lord attacks, it spawns 2 Broodlings for free. Broodlings are ground units live for 8 seconds, have 30 HP, have a movement speed of 3.84, have a melee attack of 4 damage and an attack speed of .65. A single Brood Lord can have 6 Broodlings out at once (should the enemy not kill the Broodlings), which can increase its DPS by 36. Broodlings share melee ground and melee carapace upgrades.

Brood Lords are in my opinion the strongest unit in the Heart of the Swarm campaign. The computer does not possess the AI to handle Brood Lords effectively and instead prefers to focus down the free Broodlings. Given that 10 Brood Lords can be spawn 20 free Broodlings every 2.5 seconds, it is very easy for a handful of Brood Lords to completely overrun the computer in the campaign without taking any damage. They just need Kerrigan and the Leviathan's support, which can be used to take down any air unit.

Viper - HotS Campaign Unit

Stats Before Mutations or Evolutions:

Cost: 3 supplies (total), 100 minerals, 100 vespene gas, 1 Mutalisk (Mutalisks evolve into Vipers).
Build Time: 15 seconds
Requires: Greater Spire
Class: Armored, Biological
Health: 150.
Armor: 1
Movement Speed: 2.25
Primary Ground Attack: None.
Primary Air Attack: 10 (+1) damage versus normal, 15 (+1) damage versus armored. 1.5 attack speed. Range of 6.

There are no evolutions or mutations available for the Viper. The Viper is an evolution option of the Mutalisk. There are no Corruptors in the campaign, so Vipers are evolved from Mutalisks.

Viper Abilities

• Abduct: Costs 25 energy. No cooldown. Pulls the target unit to the Viper. Enemy is stunned for 1 second. Range of 9.

• Disabling Cloud: Costs 75 energy. Places a cloud on the ground that slows enemy movement speed and prevents enemy units and structures from attacking or using energy-based abilities. Lasts 10 seconds.

• Consumption: 10 second cooldown, no energy cost. Drains up to 75 life from a friendly Zerg unit and gives the Viper 2 energy for each point of life drained.

Like the Infestor, the Viper in the Heart of the Swarm campaign is significantly stronger than the Viper in the live multiplayer version of the game. First off, the Viper actually has a mild anti-air attack in the campaign, although this does very little damage. More importantly though is the fact that the Viper's abilities are significantly stronger in the campaign versus the live multiplayer version of the game.

In the campaign, Abduct only costs 25 energy, whereas in multiplayer it costs 75. In the campaign, Abduct also stuns the abducted unit for 1 second. In multiplayer there is no stun.

Disabling Cloud is a better version of Blinding Cloud. While Disabling Cloud lasts 4 seconds less, instead of reducing units to only being able to attack in melee range like Blinding Cloud does, it prevents them from attacking entirely. It also does not effect friendly units. Disabling Cloud also applies a movement speed debuff. It costs 50 energy less than Blinding Cloud.

Finally, Consumption is an instant cast that restores energy immediately. It is much better than the Viper's Consume ability in the multiplayer.

Ultralisk - HotS Campaign Unit

Stats Before Mutations or Evolutions:

Cost: 6 supplies, 300 minerals, 200 vespene gas.
Build Time: 60 seconds
Requires: Ultralisk Cavern
Class: Light, Biological
Health: 500.
Armor: 3.
Movement Speed: 2.95 (.+88 on creep).
Primary Ground Attack: 25 (+2) damage. 1.0 attack speed. Melee range. This attack also deals 5 splash damage to nearby melee-range targets in a cone in front of the Ultralisk. This 5 damage is not applied to the primary target.
Primary Air Attack: None.

Ultralisk Mutations

• Burrow Charge: Grants the Burrow Charge ability to the Ultralisk. This allows the Ultralisk to burrow and charge towards a unit, going underground and underneath enemy units and obstacles to get to its target. Upon resurfacing, all enemy ground units in the area are thrown back and stunned for 2 seconds. There is a 10 second cooldown on this ability. It can be set to auto cast. It has no energy cost.

• Tissue Assimilation: Gain life equal to 40% of all damage dealt from normal attacks. Before upgrades, this is 10 health per swing to the primary target and an extra 2 health for every target hit by the splash attack.

• Monarch Blades: Increases the splash damage of the Ultralisk's melee attack from 5 damage per hit to 25 damage per hit. 

Ultralisk Evolutions

• Torrasque Strain: Grants the "Reincarnation" passive ability. This allows the Ultralisk to revive upon death. This can only occur once every 60 seconds. Upon death, the Ultralisk will be replaced by an "Ultralisk Chrysalis" which has 200 health. After 10 seconds, it will hatch into a Torrasque Ultralisk at full health, regardless of how much damage was dealt to the Chrysalis. If the Chrysalis is destroyed before it can hatch, the Ultralisk is lost and the reincarnation is cancelled.

• Noxious Strain: Ultralisks have an aura that deals 5 damage per second to enemy ground units within melee range. Grants the "Toxic Blast" ability, a free ability with a 10 second cooldown that can automatically cast. It deals 20 damage to nearby enemy ground units instantly.

The Ultralisk is very strong in the Heart of the Swarm campaign. While its starting DPS is a little lower than in the live multiplayer version of the game, this can be fixed via the Monarch Blades mutation. The Torrasque Strain is ridiculously powerful and is like getting 3 Ultralisks for the price of one over the course of a game. Noxious Strain is not bad either but it gets overshadowed by the strength of Torrasque. Either way players would be well advised to use Ultralisks once you unlock the Evolution mission.

Infestor - HotS Campaign Unit

Stats Before Mutations or Evolutions:

Cost: 2 supplies, 100 minerals, 150 vespene gas.
Build Time: 50 seconds
Requires: Infestation Pit
Class: Armored, Biological, Psionic
Health: 150 health.
Armor: 0.
Movement Speed: 2.25 (+.67)
Primary Ground Attack: None
Primary Air Attack: None

There are no evolutions or mutations available for the Infestor in the Heart of the Swarm campaign.

HotS Campaign Infestor Abilities

• Fungal Growth: Costs 75 energy. Immobilizes target units and deals 60 damage over 4 seconds. Reveals cloaked and burrowed units.
• Parasitic Domination: Costs 125 energy. 5 second cooldown. The target unit is permanently controlled by the Swarm.
• Consumption: No cost, 10 second cooldown. Drains up to 75 life from a friendly Zerg unit and gives the Infestor 2 energy for each point of life drained.

The Infestor is much stronger in the campaign than it is in the live version of the game. While it does not possess the ability to spawn Infested Terrans, the strength of Fungal Growth and Parasitic Domination has improved considerably. Fungal Growth does twice as much damage and is an instant cast, not a projectile like it is in live.

Parasitic Domination results in permanent mind control of the targeted unit, whereas Neural Parasite in live is limited by time and range. The Consumption ability ensures that you only need just a few Infestors even if you are constantly casting as they can restore their energy very easily with this skill. Kerrigan or Queens can then heal up any unit damaged by Consumption.

The only downside to the Infestor that mitigates its very high power is that it does require micro to use. In the campaign, a lot of your attention to micro will be controlling Kerrigan and possibly the Leviathan, which may make it difficult to use the Infestor in macro-oriented missions.

Swarm Host - HotS Campaign Unit

Stats Before Mutations or Evolutions:

Cost: 3 supplies, 200 minerals, and 100 vespene gas.
Build Time: 40 seconds
Requires: Infestation Pit
Class: Armored, Biological
Health: 120.
Armor: 1.
Movement Speed: 2.25 (+.67 on creep).
Primary Ground Attack: None.
Primary Air Attack: None.

The Swarm Host has no attacks of its own. Instead, it can use the "Spawn Locusts" ability every 15 seconds. This ability spawns 2 Locusts, which are timed ground units that live for up to 12 seconds (less if they are killed before their time runs out). A Locust has these stats by default:

Cost: None
Class: Light, Biological, Summoned
Health: 65.
Armor: 1.
Movement Speed: 2.25 (+.67 on creep).
Primary Ground Attack: 10 (+1) damage. 1.2 attack speed. Range of 2.
Primary Air Attack: None

The Swarm Host's mutations and evolutions can modify either the Swarm Host or the Locus:

Swarm Host Mutations

• Burrow: Allows Swarm Hosts to burrow. While burrowed, they cannot be seen without detection. Swarm Hosts can spawn Locusts while burrowed.
• Rapid Incubation: Rapid Incubation causes Locusts to spawn 20% faster. This reduces the cooldown of Spawn Locusts from 15 seconds to 12 seconds.
• Pressurized Glands: Locusts can now hit air units with their primary attack.

Swarm Host Evolutions

• Carrion: Carrion spawn Locusts that can fly and deal 15 (+1) damage versus the default 10 (+1). They also have 50 HP instead of the default 65 health. Finally, they move at a movement speed of 3 (no creep bonus) instead of 2.25 (+.67 on creep).

• Creeper: The Creeper Strain gains the the "Deep Tunnel" ability. This ability is free to use, has a 10 second cooldown, and a 2 second cast time. This allows the Swarm Host to essentially teleport to the target location, anywhere on the map, as long as creep is present at the target location. Creeper Swarm Hosts also automatically generate creep when burrowed. 

The Swarm Host of the HotS campaign is not nearly as functional as the Swarm Host of the live version of Heart of the Swarm. The campaign version is clearly the "beta" version of this unit that has improved significantly by the time the game finally released.

In the campaign, for some reason Locusts do not always automatically generate, meaning that you occasionally have to manually spawn them. They cannot be rallied in the same way as they can in live, making the Swarm Host unit much more micro-intensive than in the campaign. There is also no Enduring Locusts upgrade, so Locusts have a shorter range and lifespan. In the campaign, Swarm Hosts do not have to be detected in order to be seen when "burrowed". Only if you select the Burrow mutation do Swarm Hosts become cloaked while burrowed.

However, the Carrion and Creeper strains do significantly improve the strength and value of the Swarm Host. The Carrion strain in particular helps significantly as it boosts the Locust's DPS and allows it to fly, whereas the Pressurized Glands upgrade gives the Locust the ability to hit air units, meaning you can use mass Swarm Host. The only downside to these units is that they require a lot of babysitting and micro, which you have to weigh against spending your time microing Kerrigan.