Destroyer Droids (Droideka)
Trade Federation destroyer droids ("droideka" in the Neimoidian tongue) are pure nastiness wrapped up in a metallic shell. Relentless and implacable, and terrifying to behold, the droideka are the results of design and development by Colicoid designers from the planet Colla IV...frighteningly enough, the Colicoids based the droideka design upon their own bodies! Best known for getting themselves into inter-system conflicts because of their habit of eating visiting dignitaries or hapless wayfarers, the Colicoids were perfectly suited psychologically to deliver exactly what the Neimoidian contract called for: brutal and efficient killing machines.
Destroyer droids aren't terribly bright, but they do their job...deployed in wheel-mode, they are armored, high-speed balls of metal. Upon reaching the target zone, they uncurl into a semi-humanoid torso on a set of spider-like legs, while the armor plate over the droid's back is reminiscent of a scorpion's tail. Needless to say, they have a definite psychological "fear factor" about them (hence the Intimidation skill). Then they kick on their shields and start shooting...
Destroyer droids are most frequently used under very specific circumstances, and not just general combat, as their shield-generating ability makes them quite expensive (in the per unit sense). The droidekas' abilities are best used when attempting to apprehend or eliminate individuals in an enclosed or crowded area where battle droids would hamper themselves with their mob tactics (such as many areas of your typical space vessel), or to provide emergency fast-response cover-fire for positions not yet bolstered by Trade Federation forces (or, inversely, for covering retreats). Also, destroyer droids make great "sneak attack" tools. being more effective in small numbers and stealthier than battle droids. They tend to be not-so-bright, however, and can be likened to a trained hunting animal: single-minded and often overly-vicious.