This is a tricky commando mission, but it is fun as you will have the opportunity to play around with the Scrin commando, the mastermind. His ability to mind control units and buildings makes him very effective for sneaky tactics. You start with the mastermind and two devourer tanks. Leave the devourers where they are, as they are safe. Begin by collecting supply crates to the north to grab a promotion for the mastermind, effectively increasing his health. Mind control the grenadiers nearby then run to the south and east, avoiding enemy units. Keep the grenadiers in the lead, and use them to quickly clear out the garrisoned buildings.
There is a sentry tower nearby. Mind controlling a tank is a good idea, and there is probably one near where your grenadiers died. Use it to destroy the sentry tower and, if you find your tank is getting beat up, send it to the north to be killed and mind control a new tank. Hug the southern side of the map and keep heading east. You will eventually come to the corner of the map. There is another sentry tower to the north. Use another tank to finish it off, then use the mastermind's teleport ability to bring in your devourer tanks. Order them to destroy the sentry towers to the north that are protecting the barracks.
Mind control the barracks when it is safe, then train an engineer. Use the teleport ability a second time to send him just west of the power station. Capture it, and reinforcements will arrive. Use formation move to progress the large army to the northeast, toward the GDI base. When you get close, but are well out of range, start using your devastators to attack the anti-air defenses first, then the ground defenses such as guardian cannons.
Use the devastators to hit as much as you can along the edge of the base, then hit the two war factories. Retreat when they're finished, back to your army. Send them all in to attack, while you use your devastators to attack clusters of enemies to quicken the fight. Don't worry if your army fails as long as the devastators survive. As long as you've finished enough of the base, they can end the job.