Creeper Tank - Atreides Only:
First build 5 Engineers and an APC, Pile the Engineers into the APC, park the APC infront of the opponent's base. Once it cloaks, creep it slowly an inch at a time, keeping it cloaked. Once the APC is deep enough without being seen, unload it and take over 5 buildings. Sell them, you'll get infantry and money.