Your first mission on Kaldir is to reclaim the brood of the Brood Mother Nafash. This mission grants you access to the roach, and will give Kerrigan up to seven levels- five for mission completion, and two more for the additional side objectives.
As the mission opens, Kerrigan is warned by Eisha of the frost storms that periodically overtake the landscape, and warns that the Zerg units will be frozen solid for the duration. Fortunately, Sarah is able to sense some nearby lifeforms that are much more suited to the chill, and whose essence can be collected to protect Zerg units from the indigenous climate.
As you move Sarah and the zerglings that have arrived with her across the tundra, you will encounter ursadon, somewhat apelike shaggy-furred creatures local to the area. These animals are fairly bulky, but thankfully not too threatening in melee. Curiously, Sarah also notices feral Zerg that have been frozen solid- a couple of roaches at first, which she uses to bolster her forces. This is more than a little strange, though, causing Kerrigan a bit of worry.
When another two roaches are revealed encased in ice, the flash freeze hits, locking down your units- and a pair of ursadon, accompanied by a matriarch, will break through a nearby wall of ice to start attacking your force. The flash freeze ends just in time for you to turn Sarah's abilities on the ursadon. Once they are dead, collect the DNA left behind and Abathur will weave it into the swarm, causing units you control to resist the lockdown effect.
Only a short distance further on you will encounter Nafash's outpost- locked solid in ice by the flash freeze's effect and left there. Once you move Sarah into place, she will take control of the zerg present. This prompts the local Protoss base to take notice, particularly paying attention to the fact that Kerrigan is no longer possessed of the physical form of the Queen of Blades. They announce their intention to inform the 'Golden Fleet', which can be presumed to be a particularly accomplished Protoss military force, to come and annihilate Sarah and the Zerg present all at once.
Thankfully, Eisha is able to inform Sarah that the Protoss are not able to directly reach their own fleet via communications systems- they need time to prepare and operate their communications towers if they're going to get the message out. This gives you time to build up an assault force and take out the Protoss base here. Abathur will also note that more ursadon matriarchs can be found, and enough of their DNA will allow the Zerg to become stronger during a flash freeze, rather than just ignoring any part of it aside from the vision range reduction.
