I didn't understand Mummy when I finished reading the corebook. The player's section described a Tier 3 character, but the Storyteller's section described Tier 1 personal conflicts. After reading this supplement I now get Mummy: they are religious warriors, empowered and evaluated by the Judges like a fantasy RPG cleric or paladin. Ammut the Devourer is the Adversary. This supplement provides details on the Guilds that allow for Tier 2 local political play, and The Avarice Chronicle provides a Tier 3 confrontation over faith that all mummies can take a side on.
The book is split into the Intro, 5 chapters one for each Guild, two Storyteller chapters, and the Chronicle. At least one review here has criticised the Guild chapters for not having uniform layouts. I think that was done to show as well as tell what each Guild thinks is important, and to showcase different elements of the game in different chapters, which I agree with. However, having the Storyteller section contain supposed secrets is hurting the presentation of this game. Frankly, the only reason to have 'secret' info seems to be to facilitate player-vs-player conflict. The Guild chapters have lots of information from the Storyteller section of the corebook, so it's no longer secret once the players start reading this. A lot of the Storyteller material here is common knowledge and systems for the Guilds and should have been in the Intro. The Storytelling sections of this game line's books need to have less 'tools' and more advice on how to run the game.
The Guild chapters describe how the Guild operates and how they see and interact with the modern world, both to varying depth. The Maa-Kep chapter is all about getting others, whether mummies or mortals, to operate how the Maa-Kep want without realising it. The Mesen-Nebu (Alchemists) are all about lording their individualistic awesomeness over others. The Sesha-Hebsu (the Scroll) describes how they act as judges, how they carry out sentences, and how their record of history is written to glory of the the Judges, not accuracy. The Tef-Aabhi are described as the self-chosen master planners of the Arisen, whether the others like it or not.
The Su-Menent chapter is different enough that it deserves special mention. It goes into much more detail than the others on Irem itself, on the Guild in Irem, and how the Su-Menent Guild is breaking in the modern world. Like the Maa-Kep chapter, it has a section on the Guild's activities around the world, but it is less successful and bleaker outlook. The Su-Menent and Tef-Aabhi chpaters go into much more detail on Cults than the others and show how the three types can cover an incredible range of operations.
In the Storyteller's section, chapter six is game systems and new powers. It's not worth keeping from the players. Chapter seven actually has some things that should restrict it to the Storyteller. It has more Affinities and Utterances for each Guild, and something unique: relics, magic, NPCs. It also, finally, has some genuine dark secrets within Guild operations.
Chapter eight, the start of the Avarice Chronicle, is dramatic. The Heretic is the Arisen's Martin Luther and this is about taking Apotheosis public and potentially starting a religious schism that could lead to the Mummy equivalent of the Thirty Years War (which had more death and destruction than World War I). It also describes Ammut the Devourer as a more active adversary of the Arisen than the corebook makes clear (at least to me).
I don't think this player's guide is as good as similar books for other game lines. However, for me it indisuputably explained a lot of the game better than the corebook did. So I guess I have to give it four stars. Like Mage's Tome of the Mysteries, this is likely to be regarded as either essential or irrelevant.
[4 of 5 Stars!]