Strike at the zealots and sentry here, using the ursadon's Leap attack to close distance, as its damage is negligible, and then deal with the returning Protoss units you saw before- another each of sentry and zealot. Once all the foes here have been slain, Sarah prompts the larva to once again consume its host and this time, grow closer to maturity. With the added biomass from the ursadon, the larva is ready to become a brood mother- but it needs a safe place to enter a cocoon. There is a vent thankfully nearby to the Northeast- head the larva into that tube.
A beacon marks the safe location on the other end, where the larva gains the Grow ability, allowing it to transform into Niadra, the new broodmother. Kerrigan explains that she is to spawn a new brood here and destroy the Protoss- an unfortunately nonspecific command. Niadra retains the Grow command, though it can only be used with sufficient bio-mass, and gains not only the ability to burrow, but also the capacity to spawn zerglings. Once you have created as much of a force as you can, destroy the vent access plug to the Southeast and move on.
The room you have entered is full of creatures in containment, and holds only a couple of zealots and a pair of sentries to combat your forces. Slay the animals here as well as the Protoss- the animals will provide more bio-matter, allowing Niadra to grow more quickly and earlier. Continue on to the next room which holds a couple more animals, and a dangerous defence force- a cannon and a probe, powered by a pylon. Make sure to take out the probe before it can finish building additional cannon or you will be in some difficulty, but the zerglings Niadra births should be plenty to meet this task head-on.
The path to the next room is blocked by a forcefield, and Niadra is too large to continue moving through vents, but the zerglings are certainly small enough- have them break the vent plug and enter the ventilation system. The u-bend brings them to the next room of the ship, where a zealot and a sentry protect the shield's power source- have the zerglings destroy it and then Niadra can join them in the next room to the Northeast. This room contains a number of additional wildlife samples, and a defence force of one zealot, one sentry, and one stalker. As you set about destroying these and collecting more bio-matter, Niadra notes that a strong power source is in a room nearby to the Northwest- and there is another vent that leads there.
The zerglings will encounter another sentry and a cannon- and the ship's warp core. Have them break the power source for the shield at the room's entrance and Niadra can come through to attack and destroy the ship's warp core. Return to the Southeast and you will encounter a Protoss force of three each zealots and stalkers supported by a pair of sentries. Slay them to escape the dangerous area that will be damaged by the warp core breach via the Easternmost door.
