Invincible
Required: Atreides, Level 5 or higher, High Tech Facility, Repair Facility.
Build walls around the Repair Facility to block the entering passage, and Build a Carryall with the High Tech Factory. then damage one tank or any vehicle until the damage meter gets yellow, the Carryall transport it to the repair facility, and automaticly put it back. now the tank is invincible, when your unit approach the enemy base, they didn't notice you, by any chase destroy all buildings. only a unit will attack you if you attack him.
NOTE: Invincible is only able with Atreides and level 5 or higher.