From publisher blurb:
A dark star fell from the sky bringing with it the end of all things! The sanctity of the world known as Abaddon was shattered when a global apocalyptic event of a meteor impacting the planet causing a destructive ecological and eldritch change. Now there is no day or night, just never ending Apocalypse. An undead world ruled by fear and horror. Inevitably, in campaigns set in Abaddon, player characters will die. No matter which campaign model you use, it will overflow with mind-shattering horrors and lethal threats. Expand the already interesting and unusual races of the world of Abaddon. Inside this sourcebook you will find you’ll need to embark on adventures in the exciting setting of Obsidian Apocalypse:
All New Racial Archetypes for each of the Obsidian Apocalypse race ibcluding: Guardian Angel (cleric), Abaddon Pariah (ranger) , Harrowed Predator (barbarian) Hemotheurgical Leech (sorcerer) and Body Snatcher (rogue)
All New Greatwork: Mobius Body and Augmentations (Mobius Body)
And much more.