From the Product Description:
From out of the dark and forbidding heavens hurtles a great meteor, black as night itself; it carves through Abaddon’s atmosphere, calves into massive sections and rains down upon the world in great shards. It obliterates cities, shatters the living rock, sends tidal waves swamping over islands and drowns the coasts, ignites volcanoes, and sets the ground quaking. Eight in ten or more of the sentient population of Abaddon are killed in moments. No sorcery, no prayer, no force of arms, nor cunning with the builder’s craft can stand against the destruction. Those who survive find themselves in the ruins of civilization, surrounded by the corpses of their nations, overwhelmed by death, and living beneath a soot-black sky. Their suffering does not end there.
This short PDF is more of a sampling of the setting than the setting itself, which is scheduled to be released later. These pages deal specifically with the history of Abaddon.