From the publishers blurb:
he Isle of Eldisor Hexcrawl Campaign Cyclopedia & Gazetteer is a 76-page campaign guide describing the Southlands of the Isle of Eldisor.
Jordvann was once a land dedicated to Law and Good, until the rise of Eldisor, the Devil’s-Son, who together with his hordes of giants, dragons, trolls, ogres, orcs, and goblins conquered the land, reduced the people to slavery, and brought down Fimbul Winter, which caused empires to fall world-wide. Eldisor ruled for 400 years, until he was slain or brought low during a rebellion of his captains, the Old Evils. Fimbul Winter ended, and civilization rose again elsewhere, while the survivors on the Isle of Eldisor sought to stay alive between the warring Old Evils.
Now, descendants (or claimed descendants) of exiled Jordvanner have settled the southern verge of the southern portion of the island, building colonies and rebuilding civilization among the monstrous and savage peoples of the isle. Little is known of the Isle of Eldisor, and what little is known is merely myth, legend, and rumor. The adventurers can partake of the return to the Isle of Eldisor in many ways – find and recover the lost treasures of the ancient civilization; discover, ally, and trade with the savage descendants of the Jordvanner; battle the remaining hordes of evil giants, dragons, trolls, ogres, orcs, and goblins; or seek to re-establish the lost realm of Jordvann and protect the native peoples from the inroads of the colonial factors.