The B3 ultra battle droid was based on the B2 super battle droid model, though it was far larger and bulkier than the B2, and boasted more substantial armor. The B3 had two large primary arms: the right arm, containing a tight-spray flamethrower; and the left arm housing a wide-spray plasma cannon. Two smaller secondary arms, located underneath the primary limbs, featured deadly rapid-fire forearm blaster cannons, similar to the B2 battle droid.
Built into the droid's left shoulder was a missile launcher containing brilliant missiles, capable of highly sophisticated target acquisition and tracking. The design also featured a Density projector, a device capable of increasing the droid's weight twenty-fold. This enabled it to lock itself in place and made it nearly impossible to topple over, counteracting the droid's high center of gravity, although doing so would make it an easier target for Republic heavy weapons.
- "…but clearly, even your acrobatics weren't enough to stop that thing."
- ―Saesee Tiin to Mace Windu at the Battle of Iktotch
The B3 ultra battle droid was by far the deadliest single battle droid manufactured by the Trade Federation. Thankfully for the Grand Army of the Republic, the droids suffered from technical problems and were never mass produced.
Wat Tambor had held a challenge for two teams, Metalorn and Foundry. Foundry had developed a droid known as the Avatar-7. This was the droid which received General Grievous' blessing. It was dubbed the B3 and was commissioned as a frontline battle droid. Baktoid Combat Automata never visualized having them sent into combat in large numbers like B1-Series battle droids, owing to the B3's high cost per unit. B3 units were used by the Trade Federation for frontal assaults against well-defended targets. They were often used in place of droidekas, being far cheaper than the destroyer droids.
Jedi Masters Mace Windu and Saesee Tiin faced the Avatar-7 prototype at the Battle of Iktotch. Though their individual skills were not enough to overcome the behemoth, the Jedi worked together to defeat it, eventually destroying it by crushing it under the remains of a Hailfire droid. B3s were also used during the Outer Rim Sieges, where they served as sparse heavy units under individual Separatist commanders. However, exorbitant manufacturing costs and persistent malfunctions with the droid's density projectors prevented widespread use.
- "Heavy Metal Jedi"—Star Wars: Clone Wars Adventures Volume 1 (First appearance)
- Star Wars Episode III: Revenge of the Sith video game (GBA/DS versions)
- The New Essential Guide to Droids
- Threats of the Galaxy
- The Complete Star Wars Encyclopedia
- Star Wars Galaxies Trading Card Game – Threat of the Conqueror (Card: Shien Deflection) (Picture only)
- The Essential Guide to Warfare