Special Occasions: 1. The Not-So-Sinister Sponge
Kendrax was a planet that was once visited by Romana II.
Romana had gone to Barastabon to get a cake for K9’s birthday. On the way back, a time storm forced the TARDIS to Kendrax, where The Master, the Daleks and the Cybermen had formed an alliance. Romana defeated them and returned to the planet of sweets where the Fourth Doctor and K9 were waiting for her. (Special Occasions: 1. The Not-So-Sinister Sponge)