Droideka

Droideka's are part of the Trade Federation army, and had a reputation of deadliness, General Grevious favoured the droid thanks to it's reselience and firepower. The droid is armed with two twin blaster's and a shield. The droideka was nicknamed destroyer droids by the Republic, and they even made Jedi retreat.

Before the Naboo
The droidekas were used before Naboo, they were used in an attempt to annex Alaris Prime and expel the Wookie's trying to colonize it, but the Wookies with the help of the Jedi managed to repulse the Trade Federation forces.

Invasion of Naboo
The trade federation used the droideka's board the Saa'ak flagship, to stop the Jedi from getting to Nute Gunray. It worked, just two droideka's made the Jedi retreat. They were next used during the invasion of Naboo. They were responsible for massacring Gungan warrior's and destroying the shield generator during the battle between the Gungan's and droid army. However, Anakin was able to destroy the Droid Control Ship, disabling the droideka's.