This pdf is 32 pages long, 1 page front cover, 1 page SRD, leaving 30 pages of content.
It should be noted, that although extensively bookmarked, the bookmarks don't work in my copy of the file.
The full-color book kicks off with 3 pages of artwork/introductory quote, adhering to the OT-layout.
After a bit more than 1 page of introduction to the H'laqu, featuring exciting and cool prose, we already dive into the creeping corruption of the H'laqu in the form of new Taint and Ritual feats. (~4 pages)
The feats are:
-A Stitch in Time (Ritual): Close an extradimensional rift. Damn cool feat, but I would have loved to see DCs for concentration checks to maintain the ritual while under attack, as this is exactly what I'd do with it: Make PCs defend the ritualist.
-Bait: With a Bluff check vs. Will save, you can anger enemies and provoke them into attacking you. Nice feat.
-Black Blood (Taint): Makes you immune to poisons and diseases, but the DM may choose a drawback. This would be totally OP, but due to the drawback as well as the fact that in OT, poison and disease are ever-present, this feat works.
-Black Whip: Use whip-like rifts in reality as weapons. Stats for the weapon are provided and the point is: Black Whips ignore armor and only the +X bonus of magic armor provides any benefits against them. While not entirely conform with PFRPG-design, this is also a nice throwback to the days of second edition and thus I can't really criticize it. If you're diehard-set on "new" rules, note this.
-Cult of Black Glass: Become a member of the cult and gain access to its resources. Standard membership feat.
-Empty of Life: You are soulless. Nice rehash of the "Hollow"-feat from RL.
-Experiment (Taint): H'laqu experimented on the character, giving him/her a monster ability, but also disfiguring him/her. This is actually a nice storytelling device as well as versatile as hell. Due to being subject to DM's approval, balance is fine, too. Great idea.
-Eyes in the Darkness: Gain true seeing due to a traumatic experience, but your will save may never be higher than your level. Due to Prerequisite: WIS 18+, this feat may actually work, although true seeing is still quite powerful.
-Eyes of Darkness (Ritual): Summon Corvidim to do your bidding. Nice.
-Fugue: Enter a trance-like state that grants bonuses, but after completing a set task, the DM gets control of your character untill the end of the Fugue. Awesome idea, nice mechanics (although I would have prefered them to scale with levels) - nothing to complain about.
-Full of Life/Unlife: Gain more HP, be repugnant to the H'laqu
-Hag-ridden (Taint): The character is inhabited by a contained fragment of the H'laqu, drawing on its power. Great roleplaying potential there! Two thumbs up.
-Hand from beyond (Taint): Gain an additional, incorporeal tendril-attack.
-Hidden Knowledge (Taint): Tap into H'laqu knowledge for bonus in skill-checks or augury. I like it.
-Hollow Man (Taint): Gain +2 AC and +5 HP, but be destroyed when you reach 0 HP due to being only the shell of what you once were. I can see this a consequence for resurrecting a PC in my homebrew campaign - Another great feat!
-Horrific Countenance: Gain a Fear Rating. This feat is problematic, as its only benefits refer to a mechanic originally from "Darkness & Dread", reprinted in "Horrific Fears". If you don't own one of these books, the feat won't do anything for you, as the Fear Rating rules are not summed up in this book. Usually I wouldn't be bothered if that's a part of the setting, but the rules are not in the Campaign Setting book for OT, which somewhat limits their availability to OT players and DMs.
-Mark of Darkness (Ritual): Only for H'laqu cultists, this feat lets you call the attention of the dread H'laqu.
-Numb the Mind (Ritual): A ritual to steel one's mind against the darkness, this unfortunately also uses the Fear rating mechanics.
-The Bitter End (Ritual): Prepare a shard of Obsidian to summon a Abyssal Arm. Nothing to complain, cool concept.
-The Gap of Worlds (Ritual): Ritual that helps H'laqu create a new breach.
-The Gone (Ritual): Summon a black man of the H'laqu.
-Withering Stare (Taint): Stare at an enemy to give him penalties. As there is no save against this penalty and no drawback, this feat seems kinda strong to me.
After that, we get new spells:
-Antilife Bolt (Wiz/Sor 3): Temporarily reduce maximum Hitpoints of enemy. Cool spell!
-Antilife Ward(Clr/Pal/Wiz/Sor 4): Create a warding zone antithetical to creatures of this reality.
-Become Shadow (Sor/Wiz 6): Sperate one's shadow from the body and send it towards enemies.
-Beyond Alignment: Ignore alignments and its restrictions for some time - might have consequences. Unfortunately, this spell only lists as level 8, but does not say for which spell-lists it's supposed to be.
-Black Meteor Shield (Sor/Wiz 4): Gain a shield that damages attackers and gives a bonus to AC.
-Black Meteor Strike (Sor/Wiz 6): Damage spell that creates damaging terrain.
-Black Pit (Hiding place between the Planes) (Sor/Wiz 6): A sanctuary that might be invaded. Cool spell.
-Black Sand (Sor/Wiz 5): Engulf and suffocate enemies in damaging sand. Cool terrain control/battle magic.
-Black Talons (Druid/Ranger/Sor/Wiz 3): Ignore the additional protection offered my magic items. This spell can, depending on the setting, be extremely powerful. In OT it works, but I'd caution anyone to use it in another setting.
-Dark Eye (Sor/Wiz 5): Nice Scrying spell.
-Emptiness (Brd/Clr 2, Sor/Wiz 3): Automatically fail the next will save or save against H'laqu infection.
-Face of Fear (Brd/Clr 3, Sor/Wiz 4): This spell once again utilizes the Fear Rules mentioned earlier in the review.
-Immaculate Dissection (Brd/Sor/Wiz 4): Gain a bonus to damage and attacks against a creature. more importantly: Be able to look up the write-up of the creature. I hate metagaming feats, spells and mechanics like looking up critters, knowing the abilities of enemies etc. and thus loathe this spell.
-Insignificance (Clr/Sor/Wiz 8): Makes one experience the horror of one's insignificance, temporarily shaking the target and planting suicidal tendencies in them. Great concept for a spell, cool execution.
-Life Sign (Clr/Pal/Sor/Wiz 4): Essentially a circle of protection against H'laqu.
-Mind Trap (Brd 4, Sor/Wiz 5): Create either the illsuion of a fighting challenge in one's mind or a puzzle for the recipient to solve. Quick and dirty rules for the fight and puzzle are also given. NOW we're talking. This is what a spell should be: Iconic, cool and versatile and full of nice potential.
-Planar Shears (Clr/Sor/Wiz 5): Shear connections of planar creatures - Great storytelling device and useful in battle, although stripping planar creatures of all supernatural abilities, albeit temporarily, might seem a bit harsh.
-Shardstorm (Drd/Sor/Wiz 5): Both shield and a way to attack enemies.
-Squirming Maw (Clr/Sor/Wiz 9): Combination of Swallowed by Darkness and some Abyssal Arms. I like it.
-Sterilize (Clr/Drd 3, Sor/Wiz 4): Kill all germs in an area, curing diseases, but also weakening the immune-system of the recipients.
-Swallowed by Darkness (Sor/Wiz): Massive Annihilation spell that DOES conform to PFRPG standards and instead of insta-killing recipients, deals massive amounts of damage. This spell rocks.
-Void of Despai (Clr/Sor/Wiz 5): Grants penalties to enemies, does not specify which kind of penalty though. I guess that's the reason for this spell being such a high level - it's supposed to stack with other spells.
-Whirling Void (Clr/Sor/Wiz 8): Burst Swallowed by Darkness with a sucking effect. Nice.
-Whispering Madness (Brd/Sor/Wiz 6): A curse that slowly drives the target insane. Very cool.
There is also another nice sidebar with aptly written prose, granting us more glimpses at the world of OT.
We also get new monsters, prefaced by the H'laqu creature type, which is surprisingly well-thought out: They are susceptible to normal weapons, but resistant to spells and magical weapons. Nice idea to make PCs drop that killer blade and take up the pitchfork. I really like that each monster comes with three quite extensive adventure seeds that are more detailed than "Kill X" - a nice innovation I hope will continue in future books of OT. Each monster comes with its own, original and simply gorgeous artwork. Even for the beautiful OT-line, these artworks rock and are on par with Paizo and WotC.
-Abyssal Arm (CR 6): Thorny, dark appendages that seek to crush and draw the mortals to their doom. The seeds are very good.
-Bacterial Macrobe (CR 3): Giant floating bacteria. How cool is that? Oh yeah: The adventure seeds rock, too!
-Black Glass Mites (CR 2): Actually a swarm, this vermin is a nice way to slowly introduce the H'laqu at lower levels. Their adventure seeds are nice.
-Black Man (CR 8): Fully infected creatures, these could work as a kind of H'laqu boogeyman. Their adventure seeds are once again, top-notch.
-Corvidim (CR 2): A take on crows with a hivemind. Ok and has some nice story-telling potential.
-Infected Land (CR 5): A quite versatile piece of H'laqu-tainted land, this mobile piece of corruption ranks among my favorite critters from this excellent bunch. The adventure seeds once again provide ample inspiration.
-Meteor Golem (CR 15): Quite powerful and cool take on the Juggernaut-from-the-stars-trope.
-Nyxsus the Surgeon (CR 30): This is it. The major player of the H'laqu. The one to stand up against Calix Sabinus and the like. Of all the high-CR-major-players of OT, this is by far my favorite. Why? Well, because his mechanics are interesting. This CR 30 guy has an AC of 10. And under 200 HP. And is still a credible and terrible threat due to the cool defensive abilities and the feeling that he is truy unique. Great job! His seeds rock, too.
-Viral Macrobe (CR 4): Big, bad flying viruses that can reproduce. Fast. With your HP. Damn, I love them. Once again, the seeds are inspiring.
-Void Elemental (CR 5): Free floating holes in reality that are sentient. Nice, but my least favorite of the critters. The seeds, again, are imaginative, though.
After that, we're introduced to the cult of black glass, the aforementioned H'laqu cult with information of the H'laqu as deities for clerics as well as three more adventure seeds.
The H'laqu-infection their very presence may bring to mortals, is detailed in a three-stage process, resulting in verious bonuses and penalties and culminating in a kind of new racial template, the so-called "Shattered". I like how the infection is handled and how at the last stage, there is a sliver of hope to retain a piece of one's personality when becoming one of the shattered. Once again, rules for immunity as well as adventure seeds are provided.
The final two pages of the book detail breaching points and their mechanics, I.e. places where the H'laqu have rent time, space and magic. Characteristics are provided and sufficiently creepy, as are the adventure hooks.
This book is beautiful and follows the nice Obsidian Twilight layout and the monster artwork ranks among the best I've seen in any 3pp's books and even on par with some Paizo/WotC-artwork. Editing and formatting have improved significantly in contrast to the older OT-books, I noticed no formatting errors apart from the one spell and almost no typos. More importantly, though, there is content: Expertly written fluff that gives one glimpses of the world of Abaddon and the H'laqu. Plus: This book actually IS rather horror-themed and the monsters reflect this: PCs have to fight intelligently to defeat these critters.
So let's get to the crunch: Some of the feats, especially the rituals, can be considered plot-devices and I actually like them for what they do. They would have benefited from more concrete rules to disrupt the rituals/keep them up while being attacked/shot. I would have liked to see more taint-feats in place of the ones that use the Fear Rating mechanic, which I quite frankly think, shouldn't be in this book, as it's not part of the standard OT-rules. What I was missing, were psionics as an established part of the world of Abaddon that just, at least to me, scream H'laqu. Now, with Psionics Unleashed out, it would have been awesome to see them get some Lovecraftian love. Perhaps in an additional pdf? The spells are vastly superior to those in the campaign setting: They have their unique flair, some are downright clever and I enjoyed most of them. The true stars of the book, though, are the new monsters, the new H'laqu-type, the information on the cult and especially the adventure seeds that are enough to design a whole campaign on the creatures. The biomechanics of the H'laqu are iconic, cool and use some very imaginative mechanics, especially in the case of Nyxsus. I would also have loved to see more biomechanics. The prose is great and I'm looking forward to reading more.
So what's my final verdict? While I love most of the content of the book, I have to acknowledge that there are some glitches and some of the feats as well as the metagamey spell don't appeal to me. However, what really irked me, was the usage of the per se great Fear mechanics without specifically mentioning it or including it in the basic OT-rules canon. Considering these downsides, I'd settle for 3 stars, but the amount of adventure seeds, the quality of the prose and the inspiring artwork, I'll settle for a 4-star final verdict. If you're thinking about a semi-lovecraftian (in the pulpy style) invasion of strange beings into your campaign setting, give this a try. For the low price, it's worth it.
[4 of 5 Stars!]