Story
Though you succeeded in destroying the power tower, the Balaur will restore it and regain control if it's left alone. Strike the other Balaur facilities as well to keep them in disarray.
After completion (spoilers)
"We must distract the Balaur from repairing the power tower." Though you succeeded in destroying the power tower, the Balaur will restore it and regain control if it's left alone. You decided to strike their other facilities as well to keep them in disarray. You destroyed the small Drana Repository units and defeated nearby Dracuni to delay their response. Everything went according to plan.