Heart of the Swarm Campaign- Skygeirr: Infested

The goal of your first mission on Skygeirr is to break its defenses- not by trying to bypass them, but by assaulting them directly.  As part of this effort, you will be given the infestor unit, and side goals can reap you up to an additional three levels for Kerrigan.

While the main goal- the gated entrance to the laboratories- is essentially secure, it is protected in part by a number of enemy garrisons- garrisons full of troops that can be infested, and guarded by vehicles that infestors can take control of.  You are given four infestors on a high platform, which you must use to take over the garrisons.  These troops will then be turned back on their point of origin and used against the enemy.

Use the Fungal Growth ability that infestors can call on while aboveground to take out the first cluster of troops down the hill without exposing your units, then burrow in so that you can move faster and more safely.  Once you have brought at least one infestor to the waypoint circle, unburrow it to take control of the garrison buildings.  The garrison will start spawning and directing infested Terran troops down the hill towards the next garrison- and a banshee waiting in defensive hover.  Use an infestor to take control of the unit, and you can use it to support the less-durable infested soldiers.  There is a second garrison only a short distance further along, and then the path turns to the Northeast- and a larger Terran base.  Two diamondbacks are here, excellent prey for your infestors' control ability, as well as a couple of barracks, a factory, and two bunkers.  The platform here is very large, and also includes the necessary for a starting base- eight mineral patches and a pair of vespene geysers.  Let the infested terrans take out the enemy base- your main concern are the bunkers (which will make your job unnecessarily long) and the third garrison, which is positioned at the Northwest edge of the large platform.

Once you've moved an infestor into position to take the third garrison, and the enemy base is destroyed, the Dominion forces will open a series of vents in the floor, releasing a gas that destroys the infested Terrans.  They have a limited supply, however, and the gas apparently does nothing to your Zerg troops or stolen vehicles- so you can use the time during which the gas is being expelled to build up your forces for an assault.  A good hand at reinvesting your resources in accelerating your gathering is needed, and it helps that you don't have to worry about an enemy assault for the time being.  As an additional positive note, the gas only works for a limited period of time, after which Abathur indicates the base will need to manufacture more- that will be your attack time.