Human colonies were established on this planet of dark forests and grassy plains not once. But every time the people there started to going mad, tearing themselves and their neighbors apart in the bloodshed rampage. In 999.M41 the expedition of Technoarcheologist Dominus Ivasnophon started the excavations on this planet to reveal its secrets.
A short period after beginning of the excavations, during the first phase of the Diamor Campaign planet was attacked by warbands of the Crimson Slaughter and Titans of the Legio Excruciatus. Located on the planet Adeptus Mechanicus forces (mainly Skitarii) and their allies — House Raven, Cult Mechanicus and Legio Metalica took a big losses.[1a] After that on the planet descended Blood Angels who arrived to defend the system. Firstly Crimson Slaughter were dispersed but suddenly another Chaos armada entered the Diamor system and forces of the Kharn's Butcherhorde made planetfall on Amethal, in raw rampage pushing back the Blood Angels and their allies.[1b] Only arriving of Sanguinor saved the situation though only for short time because on the planet descended Black Legion of Chaos Sorcerer Xorphas who started the mysterious ritual. It appeared that Ivasnophon looking for the strange Chaotic structure-complex here, so called Daemon cage trying to subsides down its energies and defend it from the Chaos grip. But army of Xorphas — Hand of Xorphas clean up the path for him, and with using of Chaos Artifact — Banshee Stone he shattered the wards of Daemonic Cage. Strong was attacking impetus of Imperial forces and though they managed to force Black Legion to retreat, wards of Daemonic cage was so damaged that it's only a matter of time when Daemons will break free here.[1c]