Note As a Patreon backer helping to fund these supplements, I paid the full price for this product.
The Diviner's Handbook is the fourth release in the series of supplements for the Spheres of Power system, and this time, the focus is on a utility sphere - Divination. Unlike the three previous releases (for the Nature, Telekinesis, and Destruction spheres), this Sphere sees limited use in combat and isn't very fast (a normal Divination takes 10 minutes, or 1 minute with the Fast Divination trait - still functionally useless for combat, or even a 'quick check' of someone the PCs are dealing with, which is completely intentional).
However, this handbook might just have made Divination the most powerful one-talent dip in the entire Spheres of Power magic system, because now every single other Sphere has one or more alternate divinations. If you know Alteration, you can look for shapechangers. If you know Conjuration, you can check for outsiders and abberations. If you know Light, you can get a bonus to Perception checks.
This is probably Spheres' greatest strength - the development of powers makes sense. In Vancian casting, you can spend your entire career learning spells that have essentially no relation to one another. Here, the divination abilities you gain match what you've already trained in - so casters with a broader focus benefit more.
While the book isn't quite perfect (the Divine Dark alternate Divination and the See In Darkness Advanced Alternate Divination seem to do pretty much the same thing, and there's the occasional, slightly odd choice of wording, particulary for the Psychic Medium's Perceptive ability), I remain extremely pleased with this book. Divination may not sound interesting at first, but The Diviner's Handbook greatly expands a player's options and offers so much versatility that it's almost harder to not take Divination at some point in time. These releases remain outstanding, and I'm looking forward to the next release in this series.
[5 of 5 Stars!]