The way I read it, when you cast the power you select a single friendly unit. That unit immediately receives benefit of Create Fog, retaining it until the unit moves or the Duration elapses, whichever comes first.
That unit is then treated as the AoE for the effect, where any enemy unit that targets a friendly unit on the other side of the fog cloud(drawing LoS through it) has to deal with the Enhancement Cover 2 for their target.
The way I read it, when you cast the power you select a single friendly unit. That unit immediately receives benefit of Create Fog, retaining it until the unit moves or the Duration elapses, whichever comes first.
That unit is then treated as the AoE for the effect, where any enemy unit that targets a friendly unit on the other side of the fog cloud(drawing LoS through it) has to deal with the Enhancement Cover 2 for their target.