Heart of the Swarm Campaign- Skygeirr: Phantoms of the Void

With the presence of Protoss loyal to Amon and Narud exposed, your goal here is clear- slay the Protoss and kill Narud before they get the chance to resurrect the Xel'Naga.  This mission grants three large rewards- four levels for Kerrigan on completion, another three if you fill all the bonus objectives, and, at long last, access to the ultralisks that aberrations have thus far been an interesting substitute for.

For the duration of this mission, you are given the use of Alexei Stukov in addition to Sarah Kerrigan.  Stukov provides an interesting group of abilities to your cause- he can spawn infested Terrans, unleash a corrosive blast that deals less damage than Sarah's Kinetic Blast but reduces the armor of whatever it's damaged, and provides an aura of increased healing for your units.  You will also start off with a pair of ultralisks reconstituted from those lost to Narud's experiments.  Your initial goal is very simple- move out your small force and destroy the Protoss fanatics to the East so that you can harvest the resource nodes they are currently obstructing.  Little in the way of strategy is needed here- your present forces are large enough that there is little the Protoss outpost can do to stop you.

Destroying the outpost will reveal that the entirety of Skygeirr base has been built on top of a Xel'Naga ruins- and Narud uses this to power himself up.  Immediately, he and Kerrigan initiate a 'tug of war' with beam attacks, Kerrigan holding the initial disadvantage.  A nearby ruined temple will be pointed out to you- Narud is using this and several other bits of ruins to empower himself and drive a fatal 'null zone' towards Kerrigan.  Your goal is to destroy these temples so that Sarah can overpower the servant of Amon.

For the rest of this mission, Kerrigan is occupied dealing with the beam attack, so you're going to have to operate with just Stukov and whatever forces you can muster.  Immediately invest in a small attack force- there's a very nice potential secondary base to the East of your starting location, and the Protoss ground troops cannot reach your main outpost without traversing through it (which thus makes guarding both considerably easier).  Keep an eye on the meter at the top of the screen as you do, though, for the closer the fight gets to Kerrigan, the less time you have in which to do anything.