Heart of the Swarm Campaign- Umoja: Rendezvous (Part 2

Each of the caves is camped out by at least two marines and a firebat, and there are Terran bunkers dotted around the landscape- particularly on the raised or lowered areas where the caves can be found.  Sarah’s Kinetic Blast power is key to getting through these, as without it you will lose a lot of zerglings to the marines inside, who have extended attack range thanks to the bunker.  Crushing Grip is needed to deal with the flamethrower-toting firebats and hellbats, but can also be used on the occasional tank or goliath to boot.  Expect a lot of casualties and do whatever you need to in order to keep pumping out zerglings- without any of them at all you’re looking at a very long slog of a mission.

Once the timer runs out, several nydus worms will erupt, depositing additional zerglings and queens all over the area around your base.  The map will also open out, expanding to include a lot more territory.  If you haven't already, now is the time to destroy the Terran base, because it will continue sending units to assault your structures as long as it exists.

Your final goal is the Drakken Pulse Cannon, which is in a fortified Terran base in the Northeast corner of the map, across a mechanical bridge.  Build up as much force as you like and then sweep up there to take out the cannon and end the mission.  Tactics really aren't much needed for now, as not only do you lack the more advanced units required for tactical combat, your maximum force allotment is far larger than anything you're going to face from the Dominion.  It may be to your advantage to turn your units on the cannon while ignoring the nearby buildings- while they can obstruct you a bit with the units they produce, the Drakken is thankfully a very frail piece of anti-ship artillery and will explode before taking very much punishment.

If you are inclined, there is an additional Terran base to the far East side of the map you can destroy, but there is no particular benefit to doing so before going after the cannon.  There aren’t even any minerals here, and the most you’ll manage to do is waste a few zerglings battling the vehicles, a couple of bunkers, and a small group of marines and hellbats backed up by three or four medics.