An effective way of killing an enemy ACU is using gunships. To do this, what you need are: * Air Factory(s) * Air supremacy * Tech 1 Engineers * Land army to keep the enemy at bay * Knowledge of the Enemy ACU Location What you need to do is build 10 Tech 2 gunships and enough interceptors to give gunships long enough to take out the enemy ACU. Put T1 engineers on each factory to speed up the process. Then, locate the enemy ACU and concentrate all fire on him. The ACU should die in about 20-30 seconds, depending on the amount of gunships you have.