Grim Hollow: The Monster Grimoire is a Kickstarter product created by Melbourne Australian company Ghostfire Gaming for the 5e rule set. So did Ghostfire produce a product worth of Down Under Thunder Acclimation or does this product fizzle and fail?
To start this book is designed to support Ghostfire’ Campaign Setting Grim Hollow which was also a very successful Kickstarter product. This connection has resulted in many of the Monsters being more akin to NPC’s than Monsters but there are many unique and interesting entries with more than 400 entries to sate the desires of Game Masters.
Thematically the Monsters on on point. All come lore to support their integration into the Grim Hollow World but their lore is flexible enough that a Game Master can easily take the resource and drop it into their own home-brew campaign. In many cases the lore is very suitable for the creation of a themed one shot or singular combat encounter.
As part of the lore of each creates the Ghostfire Gaming team has provided DC checks that Players can make that allows the Character knowledge (instead of Player knowledge) be make available to the Players. While this is a nice touch Game Masters should be vary of having critical knowledge locked behind a skill check. It is usually more effective to supply a limited amount of knowledge to a player beforehand to support the horror game play this title and Grim World is supposed to support. 
Horror comes from anticipation of dread, or fear of consequence should the wrong action be made. For Players having to think and make a decision knowing they only have limited or perhaps wrong knowledge makes for a more tense playing experience. Monsters that support the horror will provide a more memorable experience.
In terms of Monsters mechanical development is on the whole very good. Most have one or more actions that provide a sense of identify to the creates without placing undue additional workload on the Game Master or Player. Additive workload is the bane of efficient role playing sessions (5e’s Twilight Cleric is an excellent example). Stat blocks are clean, efficient, and easy to peruse and aren’t allowed to stray across pages which is fundamental must do.
Artwork is good but all appears to have applied a watercolour effect that makes the images de-saturated. It is likely that is consistent with the Ghostfire art pallet and the Grimdark atmosphere that Grim Hollow campaign setting is supposed to be. Art is always a subjective critique but an 428 pages of de-saturated artwork is a bit much for me.
The Best Bit is Not the Monsters
Monsters, lore and creativity aside the reason Game Masters should purchase this book is Chapter 3: Mastering Intelligent Monsters. This 6 page section contains without doubt some of the best advice for 5e Game Masters you will ever find for running Monsters.
It does a thorough job of explaining some key 5e rules in combat that are often overlooked but it contains advice that allows a Game Master to run intelligent Monsters in a manner which makes for a more challenging combat experience for Players for a given CR in a way that that avoids pitting the Game Master as adversarial to the Players Characters.
This is pivotal advice and for those that have been listing to the 2020-2022 year of the Podcast Mastering Dungeons will be very familiar as the book sounds like Shawn Merwin and Teos Abadia during a typical episode.
In all this is a solid title if you are looking for Monsters that align with a horror genre. If you would prefer a Monster book that is more diverse (not just horror) then one of Kobold Press’s monster books may be more aligned to your needs.
