From the publisher:
In most fantasy worlds, the gods are not philosophical ideals to discuss. They are living, breathing entities that take an active role in the world. Their clerics attend to the populous. Their paladins battle evil. Blackguards seek to corrupt the righteous to follow dark masters. Divine agents come to the prime material plane to offer assistance to heroes, or to vanquish foes.
The Mythos Series allows game masters to easily construct a functional mythology to use in almost any fantasy setting. Each installment introduces new gods to help add a new dimension of storytelling potential to the game table.
Instead of just having generic deities like a "god of good" or "goddess of nature" or borrowing gods from pre-existing campaign settings, build a unique mythos for your game with these detailed yet flexible mythos concepts.