Heroes of Horror
Heroes of Horror is a splatbook for Dungeons and Dragons 3.5 that is full of useful content and advice for running horror themed adventures. It has new rules, character classes, prestige classes, spells, feats, items, monsters, and more. It's worth checking out if you are running a horror adventure even if you aren't playing 3.5. Although the book does have some good ideas in it, it's obvious that the writers didn't really understand how to make things scary.
The book introduces Cas, the moose-headed demigod of spite. Why? That's not scary. There are so many other gods in D&D that are a lot scarier and this was all they could come up with?
The book adds several new optional rules for running horror games. One of theses new mechanics is taint, which represents evil as a force that warps places and living things. Physical taint is represented by the corruption score, and mental taint is represented by the depravity score. It's largely based on the taint mechanic found in the 3rd Edition Oriental Adventures that's largely there to recreate the one found in Legend of the Five Rings. It also has optional rules for how characters may react to horrifying scenes or situations.
There were only two new basic classes introduced here, but holy shit, did they end up finding a niche. Archivist is one of the rare few Tier 0 classes, and basically is a "divine-oriented wizard", including the need of a prayerbook (aka divine spellbook) to keep up with their spells. Dread Necromancer is objectively the best "true" necromancer type class in 3rd Edition, and possibly of any other edition as well.
These two classes alone made Heroes of Horror a pretty decent purchase, and introduced the optimization boards to months of fun stuff. Dread necro isn't broken without effort to do so, but when paired up with the Ur-priest and True Necromancer prestige classes, it becomes a thing of unholy beauty.
- Corrupt Avenger : One who has become obsessed with vengeance against a specific organization or creature type. The higher their corruption, they more powerful spells they gain from this class. If the corrupted avenger is a fallen paladin, they get some extra abilities depending on how many paladin levels they have. To qualify for this class, the character must have moderate taint.
- Death Delver : One who has developed a fascination with death. The character gains divine spells and abilities mainly relating to death. At tenth level, the character gains the ability to cheat death exactly 9 times. To qualify for this class, the character must have had a near death experience. Notable in that it's one of the few ways for good-aligned characters to rebuke undead.
- Dread Witch : A spellcaster who specializes in causing fear and powering themselves up using their own fear. To qualify for this class, the character must have failed a saving throw against a fear effect.
- Fiend-Blooded : A spellcaster who draws power from their fiendish ancestry. It is easiest for a sorcerer to qualify for this class and is one of the best prestige classes for a sorcerer.
- Purifier of the Hallowed Doctrine : A divine spellcaster who specializes in purifying the world of taint. To qualify the character must be able to turn undead.
- Tainted Scholar : An arcane spellcaster who gains power from forbidden knowledge. The higher their corruption and depravity, the more powerful they become. They can increase the power of their spells by paying hitpoints to use their own blood as a spell component. A character must have moderate or higher depravity to qualify. Up there with Beholder Mage, Illithid Savant and Ur-Priest in terms of sheer ability to break the game when optimized, due to being able to substitute their Taint score for their main casting stat. Since, if you are clever, it is possible to start with a massive taint score, and there are ways to negate the downsides of Taint, this class is an example of something that is flavorful and balanced right up until the point that the munchkin finds it, at which point it becomes cheese of the strongest variety.
The book introduces several new monsters. It is a bit disappointing that the book didn't have more. Most of them are actually not that scary and some are completely forgettable. Several of them probably would have been more appropriate to put in different books. Of these monsters, only the cadaver golem and the bloodrot appeared in 4th edition, and none have returned yet for 5th, though a few of them do have fans who would like to see them come back.
- Bane Wraith: A more powerful Wraith that loves to get revenge on people by murdering all of their friends and family. It can use illusions to appear to be a living person. It can read people's minds to find out who their loved ones so it can hunt them all down. Humanoids it kills come back as regular wraiths.
- Bloodrot: A liquid undead resembling an Ooze formed from the remains of somebody who died from being melted in acid. It infects enemies with a magical disease called blood fever that is difficult to cure and can hide inside of the bloodstream of anybody who is infected. Those infected with blood fever will also attract more bloodrots to them since they can also sense the location of infectees over long distances. Like many oozes, they can also split into smaller bloodrots when hit with piercing or slashing weapons. It reappeared in 4th edition, but without any of its unique mechanics.
- Bog Imp: Lawful evil Fey creatures that lives in swamps that have the ability to make people sink into the swamp and drown just by looking at them. Elves who are killed this way turn into new bog imps. They look suspiciously similar to the gremlins from the movie Gremlins.
- Boneleaf: An aberration that resembles a plant. It has razor sharp leaves and can lure people towards it with illusions. Multiple boneleaves in an area are actually parts of the same entity connected by underground nerves, so what one boneleaf learns, all the ones connected to it also learn. One of the more forgettable monsters in the book, as there are tons of other monsters in the game that can do the same things a boneleaf can and it doesn't stand out from them. An aberration that spreads itself over a large area like a plant is a great concept and sounds like it could be a big threat, but the boneleaf doesn't live up to that potential.
- Corruption Eater: An aberration resembling a ghoul with a tongue covered in small mouths and barbed tentacles in place of arms. It drains the corruption score of those it hits with it's bite attack, and it has a breath weapon that can increase the target's depravity score which it can only use after draining enough corruption. It is vulnerable to attacks by enemies that have zero corruption and depravity.
- Taint Elemental: An Elemental made of taint. It's attacks can greatly increase the target's corruption score.
- Dusk Giant: Dusk giants are man eating giants that change size depending on how much flesh they have recently eaten and get more befit from eating intelligent creatures. They can grow up to 20 feet tall when well fed, and shrink down to just over 6 feet tall when starving. Their magical abilities also increase when they are well fed, and they always are surrounded by an aura of shadow that darkens bright lights and causes despair. You might want to use this monster if you want to run an Attack on Titan inspired game.
- Cadaver Golem: Similar to a flesh golem but more intelligent. It can gain new skills and abilities by adding new body parts to itself. The cadaver golem later appeared in 4th edition, but no longer could gain skills and abilities from assimilated flesh.
- Grey Jester: Because no book of horror monsters is completed without a killer clown. A grey jesters is an evil fey creature that can permanently steal all joy from anyone who laughs or otherwise feel good in it's presence, and may turn them into slaves called bleak ones if they have less than or equal hit dice than the grey jester. If it can't make you laugh with it's performance it can instead force you to laugh with the Tasha's Hideous Laughter spell which it casts by touching you with it's hands or the scepter it always carries.
- Phantasmal Slayer: A ghostly creature that looks like the viewer's worst fear. Anybody who sees a Phantasmal Slayer is affected as though hit by the phantasmal killer spell. It's touch can cause the victim to instantly drop dead from fear.
- Tainted Minion: If a humanoid's corruption score becomes too high, they drop dead and rise as a tainted minion.
- Tainted Raver: If a humanoid's depravity score becomes too high, they are driven permanently insane and become a tainted raver. They are always angry, all the time
- Unholy Scion: If you want the villain of your campaign to be the Antichrist, this is the template you should apply to them. They are pure evil before they are even born yet. The mother of an unholy scion is permanently under the scion's control by an effect similar to the charm person or charm animal spell, even while the scion is still a fetus inside of them. The scion can also see through their mother's senses and use it's spell like abilities through them similar to a wizard's familiar. It also gains claw attacks and several spell like abilities depending on how many hit dice it has. This is the only one of the templates in the book that can be a player character, not that you are likely to find a DM who would let you.