StarCraft/Protoss mission 2: Into the Flames

Overview
This mission comes in two phases: (1) the first 15 minutes where you build your base and wait for Fenix to arrive; (2) Fenix and friends assault the Zerg forces and kill the Cerebrate. The main purpose of the mission is to acquaint you with Reavers, which (given the limited resources at your base) are required for this mission.

Phase One
As usual you find yourself with a rudimentary base. It is situated at west-center. Get to work building your economy with two probes on each mineral node. Ramp up your pylons, then start building your prerequisites for all the basic units and upgrades. You will only be able to build Zealots and Dragoons, and their purpose is really just to defend your base. Build a pylon with photon cannon at the north and east ramps.

The Zerg assaults in the first 15 minutes are mild and easily handled by your Zealots and Dragoons. The first attack is two Zerglings from the east. Then 6 from the north. Later, you'll see Hydralisks and Mutalisks, but nothing higher in the Zerg evolutionary chain.

Throughout this phase, you will also have a small force to the east, directly opposite to your main base. The assaults here, if any at all, are quite modest and do not require your attention. There are no resources here, nor can you get a probe across since the northern half of the map is divided by a river and south of that lie heavy Zerg encampments. You have no flying units in this mission, so the river is a hard barrier for your units. Fenix will spawn at the eastern camp.

Phase Two
After 15 minutes, Fenix spawns to the east with three Reavers. Although it is possible to take a large force from the west across the middle of the map to help Fenix, you will likely lose half of those groups getting across and leave your main base somewhat lightly defended.

When Fenix spawns, you will likely go heavily into debt on supplies (aka Psi) unless you have built a large number of excess pylons before his arrival. This means you will need to spend 100 minerals per pylon to catch up on Psi if you expect to build any more before embarking on your assault. Therefore, in order to optimize the economic side of this mission, you want to try and fully tech and build all your forces before Fenix spawns so you don't have to pay for the Psi he and his Reavers require. Make sure, if you decide to run out your money, to save at least 500 minerals for Scarabs later on.

The Cerebrate you need to kill is directly south of Fenix. Put the Zealots into a group, the Dragoons into another, and the Reavers into a third. Leave Fenix behind simply because you can succeed without him and if you group him with your assault, he tends to get killed unless you're very careful. If Fenix dies, you fail the mission.

If you wish to move some or all of your western units across the map, now is the time. The Zerg encampment here is quite strong, so you might want to try and move your eastern units to the center before or simultaneously to ease the fighting for a rendezvous. In any case, once you have your groups set up, it's time to move south toward the Cerebrate.

There are a lot of Sunken Colonies along the way, and without Reavers the mission would probably be impossible. Reavers trivialize taking them out, however, provided you retained enough minerals to keep them stocked on scarabs. Put your Dragoons on the Mutalisks and don't let them get kited into the Zerg base by fleeing units. You can suffer very few casualties by simply letting the Reavers nuke everything from range. To reload your Reavers, click on their group hotkey and hit 'r' enough times that the Scarab icon disappears. Move slowly and keep reloading.

Carefully manage your support units and use your Reavers to take out all defenses; you will soon arrive at the Cerebrate. He has 1500 hit-points.