Once you find the base take a larger force and attack, the base, it will not be heavily guarded so it should be easy to take it out. The Harkonnen hinder the production of Spice. A Harkonnen attack will disrupt efficient production. Inefficiency cannot be tolerated. The Harkonnen must be eliminated.
New weapons are available - the Quads.
Newer weapons are more powerful. Powerful weapons ensure victory. That is the mission. This will help to ease the Harkonnen attacks. The best units for use in this level are the new Quads and Trooper units, try to build as many as possible and send a large attack force to the Harkonnen base overwhelming their forces.