Thanks to Zsa Zsa and Wolfie for input.
They cannot exist fully in your universe of sharpness and shadows, but they fear you and have prepared an assault on your society. They have been weakening you through your media over a period of several lifetimes. Hours, months, decades of damaging information has been fed into your mind, stupefying you and making you terrified and miserable. Now that you are helpless they ready their crippling blow – Mindkill. All of humankind will be vapourized, both body and mind destroyed in an instant.
But if you have been listening to our tapes, you may be able to resist the coming Mindkill Event. A seemingly blank tape played once can have only the smallest effect against a lifetime of deafening horror. But that small effect can be built on, and you must play the tapes as often as you can to reverse the effects of media damage. If you begin to hear a voice while listening to the tape, then you are one of the few people we can help from our world of formless light.
They are aware that the Mindkill will not work on you, and so they have assembled other weapons designed to work in your environment. They will pinpoint the survivors of the Mindkill and will transport mobile killdrones to your location. We will try to send you further instructions in audio format when we detect the Event. You must be ready to move. Ensure your firearm is in working order and has a fully loaded magazine.
Help the last cult on earth survive. We are not alone.