Heart of the Swarm Campaign- Skygeirr Achievements: Infested

Normal Difficulty:

Infested (10): Win.

Master of Puppets (10): Use Parasitic Domination to control enemy units and use those controlled units to kill at least 60 enemy units during the mission.  Given that most of what you're going to get to dominate from enemy attacks is vikings and the occasional banshee or medevac, this is a rather tall order.  Bringing your infestors out to the front to gain control of thors and siege tanks is pretty much mandatory for this, but it's also a large risk with the frailty and slow recharge infestors have.  Furthermore, operating defenses and offenses while using infestors for this requires a good deal of micromanagement skill.  That said, once you have the necessary units, actually killing 60 enemy units with them is pretty much a snap- just park them outside the Terran main base and have them blow away all the enemy assault forces for a couple of gas cycles, and you're golden.

Spreading the Disease (10): Infest all of the garrisons and don't lose any virophages.  The main difficulty for this is keeping your virophages adequately defended.  No amount of planting spore colonies around them is going to keep the enemy from getting a few firebats airdropped in somewhere, so you need to have fairly quick moving troops that can deal with that.  Mutalisks are helpful for this, provided you can keep them from getting splattered by air-mode vikings, as are occasional stationed lurkers or sunken colonies.  Try to avoid relying on your assault force for defense while reaching for this achievement, as that's pretty much begging to be stuck across the map or in the middle of a fight when the enemy attack force launches.

Hard Difficulty:

Once, Twice, Three Times Malady (10):  Complete the mission before the Dominion gas the platform a third time.  Initially this may seem like a horribly difficult thing to manage- but there's a small trick to it.  You don't actually have to infest any garrisons beyond the third.  While the first three are necessary to your establishing a base in the initial location, the others are useful but not vital to completing the mission.  A sufficiently quickly built assault force with queens for sustatinability can actually pretty much spear through the enemy troops and bust open the gate of the base without having to divert for much of anything- a couple of siege tank emplacements will need to be uprooted, but that's about it.  That doesn't mean you can't plant any virophages- the added troops make the gasless times that much easier- but when reaching for this achievement your only goal should be opening a path to that gate and keeping your assault troops alive long enough to reach out and crush it.  Amusingly straightforward, but while it's less difficult than it seems that doesn't mean that it isn't difficult.