Dark Skies is the eighth mission in the Nova Covert Ops Campaign.
- Defeat the death fleet
One Woman Army Achievement Strategy
The key to obtaining this achievement is to send Nova off by herself near one of the enemy spawnpoints, preferably the ones to the sides (outside of the Gorgon Battlecruiser paths). The Apollo suit and Plasma Rifle are the best choices here and the tactic is to position her as close as possible to the spawn point, slowing down enemies as they spawn with the Plasma Rifle, retreating back towards defenses (but not all the way back to them) and repeating this until the Plasma Rifle kills them all off. By doing this, Nova can defend an entire lane all by herself and nearly all if not all the kills associated with it. Nukes will be necessary (4-6 Shadow Ops Academy are recommended) and should be used once enemies are bunched up and slowed down enough to take them all out at once with a single nuke.
It is best to leave Nova on a single lane so you don't miss any kills, but early on, you will need to, and should use her to intercept the important enemy attacks (the ones you are notified of) using the subway system. Later on, you will also be interrupted by the need to take out the Mothership, of which Nova should probably be used to deal with. After those are taken care of, placing her on a single lane will net you enough kills for the achievement.
If this approach is taken, it is advised to build up a few static defenses (bunkers, Siege Tanks, and optionally Liberators) on the two "odd" paths not covered by Gorgon Battlecruisers, i.e., the lanes inbetween them, one of which has the Science Research Center. The allied defenses in these areas are not very sturdy and if they break, the enemy will flank the defenses on the main lanes which can be troublesome. Needless to say, you should also reinforce the main lanes as well.
- Protect the science facility