Light wave sickness

Light wave sickness was a sickness fatal to the Daleks. The Daleks conquered Spiridon hoped to discover the secret of the Spiridons' invisibility and reproduce it for their own use on an army kept in suspended animation. One Dalek managed to become invisible, but died by the light wave sickness before the Dalek was discovered by the Third Doctor and a group of Thals. (TV: Planet of the Daleks)

For many years for become prisoner of the Daleks The Seventh Doctor defeated them with the light wave sickness. (AUDIO: Return of the Daleks)