Vorax is the twentieth short story published in the Horus Heresy that was not originally part of an anthology novel. Vorax was the fifteenth item released as part of the Black Library's 2014 Advent Calender. It is also now included in the Eye of Terra anthology novel.
The Ring of Iron encircles Mars like a broken halo, standing as the last contested outpost of the Dark Mechanicum inside the Imperial Fists' blockade. But those rogue Tech-priests and Adepts lurking in the depths will soon face a new enemy, and the hunters shall become the prey...
- Vorax (Short Story) by Matthew Farrer