Mission 2 - Ghosts in the Fog | Achievements - Whispers of Oblivion SC II: Legacy of the Void Guide

Ghosts in the Fog. Requires you to complete the mission on any difficulty level.

Gassed Up. Gather 3500 units of gas from the eruption sites. Very simple objective, especially since the mission doesn't have any time limit. All you need to do is gradually clear the map of enemy forces and gather the resources appearing from time to time. The enemies aren't collecting the gas, so sooner or later it will all get into your hands. The gas will appear infinitely, so the only thing that can stop you from completing this task is your own patience.

Nixed Nexus. Destroy all nexuses while playing on the normal difficulty level. This achievement can be obtained similarly to the above one. Keep cleaning the map and improving your forces. Before completing the main objective, destroy enemy bases in points [2] and [3]. During the attack on the main enemy base in point [7] don't march straight at the temple, but get rid of other enemy buildings instead. Destroy three enemy nexuses in this way.