Heart of the Swarm Campaign- Char: Fire in the Sky (Part 3)

With Kerrigan leveled up, continue to the Northeast and down another ramp- another scourge nest lurks here, again guarded by Terrans.  There are also some hellbats keeping a queen pinned in a cave- if you've been thorough, you've also gained some zerglings and banelings by opening up other caves, and the queen will be the last of the local Zerg you free up.  As you tear down the Terran defenses here, Warfield will airdrop in more troops, so be aware that more marines and marauders are incoming.

Another tertiary Terran base lurks to the Northwest of this area, guarded mostly by troops rather than bunkers.  If you can spare the time, carve out the enemy here- they've got more resource crates present and once your assault force is large enough to win any of the fights on this mission (which it should be soon if not already), you aren't likely to take any appreciable losses anymore.

Heading Northeast again, you will face a bit of stiffer opposition at the bottom of a ramp- the top (and its accompanying scourge nest) is relatively lightly guarded by some goliaths and missile turrets.  Continue South to find more Dominion emplacements scattered around and another sidepath to the Northeast.  This continues on level ground up to the second Zerg skeleton, and that area also may get bombarded from the Northwest- down the ramp there are more Terran emplacements, a few crates, and some trapped local Zerg.  These include a drone, who can be used to place a hatchery here so you can spawn a queen on-site and drop another creep tumor.  That is particularly important given that the fifth scourge nest waits for you here.

Returning to your main creep's leading edge, head due South for another scourge nest and heavier Terran emplacements.  There is one last split in the path- a ramp to the Southwest will bring you to the final scourge nest, a bunch of resource crates, and a light Dominion guard force.  Send Sarah up a small sidepath to the Northeast to gather the last Zerg skeleton, and then cluster up your forces to take out the secondary terrestrial Terran base to the Southeast.  If you get here quickly or have air unit access already, you may find you want to plunk a hatchery down here and begin harvesting- but keep in mind that without any air units you won't be able to attack the primary Dominion force at all, and even if you have them (most likely mutalisks) the base is well-protected by missile turrets and utterly untouchable when a Gorgon is lurking overhead of it.  Thankfully, by this point you've reached all the scourge nests, so opening them is just a matter of applying creep tumors at the right time, and you've pretty much wrapped up this mission.