The Empyrean Extermination Sequence is a non-nuclear super-weapon used by Cepheus, the Empyrean military, to decompress the air upward into the sky and let it go so it falls back to the surface, used to destroy Acheron. Alithea witnesses its use in To Coexist Is to Surrender and Siege while she was aboard the Cepheus Ring around Acheron[1]. Virton executed the sequence at Enyo's beckon[2].