This product begins with an overview of religious faith in the City State of the Invincible Overlord. It's quite diverse, with over 300 religions to choose from, whether you prefer one of the 50 most popular which have followings of 600,000 or more, or prefer a small cult with a handful of worshippers. As many faiths are pantheistic, the majority of citizens venerate several gods, even if they have a favourite one.
Worshippers of any given faith can be classed at one of five levels of devotion, which determines what access they have to the benefits of their belief. Irregular worshippers just pop in occasionally and will probably not even be recognised as devotees when they die, while others who attend more frequently or even become fanatical lay 'initiates' may even gain access to low-level spells as well as expect to have their soul judged by the tenets of the faith in question upon their demise. And then there are the priests, the 'professional' devotees who are normally of the cleric or druid classes with all the concomitant benefits and abilities.
These general points out of the way, the work turns to a detailed description of one religion: Forn Sidthr, also known as the Old Custom. Over 60% of City residents pay at least some respects to this faith... even the Overlord himself has been seen at services! It's a pantheistic faith, venerating the Aesir (Odin, Frigga, Thor and the like), with most devotees worshipping Odin and whichever minor deity of the pantheon suits their tastes, circumstances and gender. Most followers are of good alignment, while priests are required to follow the alignment of their chosen patron deity.
Reading on, we learn of the clerical hierarchy, religious texts and the way in which worship is conducted. There are daily prayers, with a weekly Thing and four Great Things per year as more important festivals; as well as the normal rituals most faiths have to mark birth, coming of age, marriage ('handfasting') and funerals. Most seem to involve a lot of eating and drinking. The tenets of the faith are discussed in considerable detail, and apparently the most fanatical tend to dislike both technology and arcane magic. There is sufficient material here to enable anyone who studies it to role-play even a devout follower of this faith convincingly.
The next section goes into considerable detail of the afterlife for an Old Custom devotee. While the details of the faith for the living are presented in much more detail than is common for the average game, this section is a novel take, enabling the game to continue after death as the devotee is judged according to both his life and the manner of his death... so don't rip up that character sheet immediately upon your character's demise. There's a big list of sins and virtues which are used to decide the soul's fate - and virtuous ones are welcomed into Valhalla to feast, being so gratified by this that they can even resist resurrection spells should someone care to attempt to bring them back!
Overall, this work gives exceptional detail of one faith, sufficient to make it an integral part of your game. The whole judgement of the soul section provides for a grand finale to any character's life (provided you have kept track of his virtues and sins while alive). Death may still sting, but at least you can work out where you are going!!!