Chameleon droids were a unit of probe droids during the Clone Wars. Dooku sent a batch or two of them to the Crystal Caves to find the temple of Ilum, and destroy it. They descended to the planet in hyperspace pods and found the caves almost immediately. The droids began their assault just as Jedi Master Luminara Unduli was helping her Padawan, Barriss Offee, construct her lightsaber. After sensing the presence of the intruders, the two Jedi counter-attacked, but were unable to prevent the droids from laying enough mines to heavily damage the caves. Nearby in space, Jedi Grand Master Yoda sensed the two Jedi's peril at the Crystal Caves through the Force, predicting that they would die if not rescued soon. He and his companions, Senator Padmé Amidala, her Head of Security Gregar Typho, protocol droid C-3PO, and his counterpart R2-D2, plotted the most direct course for Ilum.