It is a special attack, which left behind a cloud of corrosive substances. Units of the enemy, which caught in such a cloud, can accumulate the clots of acids, which are especially detrimental to the gun systems. A successful attack will reduce the attack speed of the unit by 50%. The percentage probability of a unit hitting is 100% * [Cloud volume] / [Maximum unit armor].
Volume cloud of Devourer: 10,000 + 10% for each level of acid evolution; the maximum number of targets: 1+[AE level]/2.
The volume of clouds of Usurper: 200000, the maximum number of goals: [Acid evolution level] * 2 + 1.