1. Do as much damage as possible during the sneak attack.
2. (Achievement) Take out a Barracks a Factory and a Starport
While tearing down the enemy structures, you’ll need to be a little picky to get his achievement. Depending on what direction you go, you might miss out on one of the specific structures. The only available Starports are to the North which will require you to travel to two different bases to destroy the enemy buildings. The Odin is slow as molasses, so factor in the time it will take you to get from one base to the other.
3. Build a base defense, repair the Odin
Once the sneak attack is over you’ll assume control of the base. Build a small defensive line at each entrance to your base, but note that you’ll suffer the heaviest attacks from whatever direction still has the most enemy buildings left standing. Also make sure to build a few aerial units for your base defense, as the enemy has an annoying habit of attacking from the elevated platform directly north. Call in the mercenary Vikings of Banshees if you don’t feel like building a starport.
4. Unlock the secret mission
The bottom right corner of the map contains an isolated red building, that when destroyed, will drop secret documents. Collect these to unlock the secret mission Piercing the Shroud
5. Assemble a ground force
As usual, a force of Marines supported by Medics will come in handy here. Make sure to include a few SCVs with your ground force to repair your Odin and Thor units.
6. Assault and hold each point.
Depending on how much damage you did during the sneak attack, at least two of the bases should be partly destroyed. As long as you keep your Odin and Thor units repaired, they can handle capturing each point almost on their own. The Marines well help solidify your advantage, but make sure to watch out for any left over Siege Tanks, as they’ll make very short work of your foot soldiers. Just send the Odin and Thor into each point first to soak up damage and then send in the Marines afterwards. Have the SCVs hold the point and park the machines on them so they’ll get repaired. Capture all three points and the mission will end.
