TL;DR: This is one of the strongest offerings in all of Fifth Edition D&D and you should check it out! I trust the authors to fix the issues I have with this release, so even though it has problems, don't let that stop you- they WILL get fixed. Sooner or later.
- Subclasses: Loved 9, Liked 10, 6 Need Work, 0 or 1 classes that should just be scrapped, depending on how I feel about Way of Atonement at any given minute.
- Backgrounds: Loved them! All of these are common enough backstories for characters, so it's great to have them detailed out like this.
- Feyblood Race: Needs work. Needs lots of work. The concept is there, the execution is terrible.
- Optional Rules: I have no strong feelings one way or the other about these. Except the stabbing-reality critfails. Those are great.
- Adventure: Loved it! Set in Port Nyanzaru, so having access to Tomb of Annihilation is almost a must, but the Death Curse is optional. Sets the PCs against the Xanathar's minions.
- Monsters: Loved them! Urban dryads can add a lot of flavor to your larger towns, and the Gen can add a lot of flavor to any campaign that use genies.
- Art: Liked it! A lot of it's recycled but the original stuff is almost as good.
- Price: Worth it.
Detailed review below! I'll review all of the subclasses first since that's what most players and DMs are here for, and other stuff afterwards.
PATH OF THE COURAGEOUS HEART: LIKED IT. If you enjoy protagonists who simply can't stand by when there's injustice, fly into a rage, and realize only afterwards they've shifted the region's politics by braining the Duke with a table leg, this is the class for you. Most all of the features play into the flavor of the good-hearted hero who stumbles into victory as much as they earn it through sheer determination. It is a bit unfortunate that the 6th level feature gives you benefits that only apply to unarmed and improvised combat, since the flavor of the class overall doesn't suggest unarmed combat as the core- perhaps an additional ribbon ability at that level would be nice.
PATH OF THE RED REAVER: LIKED IT. This class starts with a simple premise- a warrior who seeks combat because it is the only way they know how to find any meaning in life. That sort of character is easy to find in many fictions, so it's easy to see why they'd make it into a Barbarian. The additional flavor and mechanics rely on blood and the barbarian's addiction to spilling it, which gives it an overall strong flavor/mechanics cohesion. The features tend to the strong side from the get-go- Sanguine Scent, while largely a roleplaying feature, is still a strong one, and I suspect the class would be better served by merging it with the 6th level feature "Blood Hound." Sanguine Clarity lets you increase the critical threat range of your attacks by up to 3, which might make some DMs feel uncomfortable with it since Barbarians get Reckless Attack.
PATH OF THE SACRED KIN: NEEDS WORK. Many barbarians revere their ancestors, but not all barbarians can claim descent from a dragon. This class is a martial third-caster, styled after Eldritch Knight and Arcane Trickster, but its source of spells is the Sorcerer. This class is strong- TOO strong, in fact, because it always seems to gain one or two more benefits than necessary at any given level. Some of these are just plain buffs over similar features in other classes, taking that feature, and then adding "...and also it does THIS COOL THING" when the Barbarian should absolutely not be getting both of those at the same level. With some trimming, I'd give this one a gold star.
COLLEGE OF DISCORD: LOVED IT. If you've ever wanted to smash your lute over an orc's head or shank them with a flute, this is the college for you. This is a style of bard I can absolutely see spreading like wildfire throughout the community. Battaglia feature- an area "save or fall prone"- is a little too powerful as is, but this can easily be tweaked. Pandemonium is an extremely powerful ability- simultaneous haste and slow in an area around you- that attempts to balance itself by making you a sitting duck during the performance. Since it's not a spell, don't let your players talk you into letting them maintain concentration with their War Caster feat!
COLLEGE OF KEYS: NEEDS WORK. It's a classic joke that when the bard fails to pick a lock, they attempt to seduce it instead. This class can literally do that. While that image is glorious, the overall list of features is a little too specific and not applicable to every situation. I guess you could say they're KEYED to their job? Beyond just being a little too specific, the 10th and 14th level features are a jumbled mess of missing words and incoherent descriptors, but I assume the features would be cool if they functioned as intended.
COLLEGE OF MOURNING: LOVED IT. This is a bard whose performances are made to memorialize the deceased. This is a nice, simple class that looks like it fits right next to canon ones. My only gripe is the 6th level feature being ripped straight from the necromancer, but as this is a necromancy bard, that's understandable.
ENTROPY DOMAIN: NEEDS WORK. An antimagic domain whose clerics worship black holes- I mean, "spheres of annihilation." I'm not sure how this translates into advantage on death saving throws- at that point you're negating entropy. The list of domain spells is, frankly, ill-fitting, and I'd consider tossing out many of them due to a complete lack of entropy involved, or even negative entropy. If anti-entropy is the intent of the class, the flavor should say that instead.
SURVIVAL DOMAIN: LIKED IT. A domain for people who stubbornly refuse to die. You'd expect more ranger-style flavor here than there is, considering it's a domain for use by tribal races like lizardfolk. I also expected to see a Relentless Endurance-style feature. What you do get is area healing, area grant-advantage, and single-turn immunity to all damage, which aren't bad! Just not what you'd expect.
CIRCLE OF SEASONS: LOVED IT. Less colorful than their name might imply, these druids focus on the one thing that is always inevitable- Entropy. I mean, change. The flavor and mechanics here merge extremely well. They can spend their wild-shape to fuel a feature called a Shroud of Seasons, which puts a powerful debuff (or buff) on the target, which grows more powerful as you level up. My MAJOR gripe with this is that, as currently written, you lose the ability to place the Shroud over a single target at 10th level, and instead place it over an area that no longer moves with its victims.
CIRCLE OF THE SPIRITLORDS: NEEDS WORK. Despite the fancy name, this is perhaps one of the simplest classes any spellcaster has had to use. It starts out very slow, and quickly builds up in power until 14th level, at which point they are an engine of destruction that ignores resistance and immunity to 6 different damage types and knows 12 more cantrips than any other druid. I'd much prefer more roleplaying flavor in a class called "Spiritlord" to being so dramatically overcharged.
DRAGOON: NEEDS WORK. I can tell that whoever wrote this class is passionate about it. They are passionate to a fault. Please, cut down on all of the unnecessary flavor text, because I don't like wasting time figuring out where the history lesson ends and the class feature begins. Beyond just gripes that over 20% of the class is unnecessary flavor text (I counted, and didn't count Necessary Flavor Text that every class has), the class itself is an alternate to the Cavalier presented in Xanathar's, modeled after the historical dragoons. Its 3rd level features are all extremely powerful- and, in the case of Elevated Control, perhaps too broadly worded. After all, advantage on all Persuasion checks against any creature with "the capacity to be used as a mount" is dangerous wording. Its 7th level feature, Line Breaker, is perhaps an even better version of the Cavalier's 15th level feature, Ferocious Charger, and I'm not sure any of the features beyond third are placed at the level they should be. My largest gripe is that it adheres too strictly to the historical concept of a dragoon, when there is a large breadth of fantasy dragoons that could be used for inspiration- especially since you can use your bonus action to fire a loaded one-handed ranged weapon, a clear reference to pistols, which most campaigns don't have. I agree with the design philosophy that led to the Cavalier and Samurai in Xanathar's in the first place- use the fiction to enhance the reality.
RUNEGUARD: LIKED IT. This is a unique class that takes aspects from rune magic previously shown in Storm King's Thunder and applies it to a Fighter. It functions a bit like Eldritch Invocations, except each is usable only once per short rest. Two suggestions/complaints: 1) Stein-Hagr can't give you advantage on death saving throws, you lost concentration on it when your HP hit 0. 2) A personal gripe: Stacking the burns from Ild-Sokn can lead to an absolutely ridiculous amount of damage if you combine it with spells like Bestow Curse to prevent the enemy from putting them out. I'm not sure if that was the intent of the ability.
WAY OF ATONEMENT: NEEDS WORK. This is perhaps a textbook case of what sort of class not to allow a Munchkin to get their hands on. This class gains an extremely powerful smite-style feature (2d8 per Atonement Die spent, you can use half your level per smite up to your total number of levels), in exchange for taking 1d8 damage for every die you spent on smites during your adventuring day during your rests- when you choose to atone, of course. Having a resource system separate from the concept of short or long rests, which damages you when you refill it, is quirky and costs your healer a spell slot at best, and can severely decrease the monk's fighting potential for days at a time at worst. It also magically bonds to a club (any club), and gains a variable +1 to +4 to all attack rolls, damage rolls, and saving throws made while the club is equipped. This stacks with the club's innate bonuses. Perhaps at odds with the class itself and all other monk classes, the 17th level feature is a skillmonkey feature, allowing you to "smite" your ability checks and saving throws. I'm almost tempted to give this one a "Scrap" rating instead, the only one this book would earn. I don't know what this was based on, but it was clearly based on something and went too far in the name of perfection. Dial it down, make it fit, and we'll see where it goes.
WAY OF EMPATHY: LIKED IT. This class damages themselves on purpose too, but unlike the Atonement monk, they actively spend their hit points in order to heal and protect other characters nearby. Think of it as the Warding Bond spell expanded to cover an entire class. It's a great way to play a more pacifistic monk character.
OATH OF PREDATION: LOVED IT. This class screams "Use me as an archvillain for your campaign!" Based on the Illrigger Paladin of D&D's past, the Oath of Predation has the Paladin become the head of their own cult of personality. Or a Thieves' Guild. Or both! This class adds a lot of sneak flavor and uses for your otherworldy charisma that combine to make you a formidable ally to the Trickery Domain, the School of the Beguiler (also in this book), and Rogues in general.
OATH OF PROVIDENCE: LIKED IT. At first glance, this seems like a class similar to the Courageous Heart- someone who fights against evil, no matter the odds. The Oath, however, makes the Paladin accept that some things can't change- but the things that do change are the will of the gods, and you are their instrument. All of its spells and features are centered around luck and destiny, making it a Divination specialist on par with the Divination Wizard, Wild Magic Sorcerer, or a Halfling with the Lucky feat. The 20th feature is extremely powerful, and might be best trimmed down a bit- starting with the "recharges all other features besides this one when it ends" bit, which no other Paladin gets.
BURGHAL EXPLORER: LOVED IT. Other than the name (really? You couldn't go with Urban Explorer?), it's a solid class with unique concepts that take advantage of its theming and flavor. It can cast find familiar too, so your Batman Ranger can have their own Robin. Of note, the text accidentally calls it the "Ruin Dweller," which I think is a reference to the next class.
WASTELAND WANDERER: LOVED IT. This class is designed around the concept of being the party's Mom-friend, and that's okay. After all, someone has to make sure the food isn't poisoned, spot the bad guys in the bushes, check for all the traps before they allow you into the room, kiss your booboos to make them better, and shoot someone in the face for daring to hurt you. On a side-note, don't let your players take this class in addition to the Observant feat. You will regret it.
DIVINE HERALD: LOVED IT. This class hits the sweet-spot of flavor, mechanics, and ease of use that make good classes into great classes. This Rogue is a third-caster like the Arcane Trickster, except it takes from the Cleric spelllist. All of the flavor and combat features add to the class exponentially and I can imagine having so much fun playing as one. My only gripe is that your choice of spell-schools aren't limited like other third-casters, but that's an easy fix.
FEY MAGIC BLOODLINE: LIKED IT. This class fills a sorely-needed hole in Sorcerers and gives them access to druid spells as they advance. Oddly, that and the Sylvan are the only features they get at 1st level, but access to healing and other unique druid spells is potent enough that I'll forgive this, especially since the higher level features are very potent.
CHAOS PATRON: LIKED IT. There are no words for the sheer level of chaos this patron adds to a game, except, perhaps, "Use At Your Own Risk." They don't use a d100 table like the Wild Magic Sorcerer does- instead, they have several d6 tables, one for each of their class features (except 14th). The 1st level feature can put a damper on your whole adventuring day with a bad roll, especially if you rely on ranged spells. That said, the type of person who would willingly use this Patron is the type of person who is either willing to take on these risks or is a horrible compulsive gambler.
NOBLE GENIE PATRON: LOVED IT. While I've never played an Al'Qadim setting, I know enough of the lore to recognize a Sha'ir when I see one. I suspect, however, that getting the ability to cast literally any spell (almost like a wish- oh, I get it!) was not part of the original class. I'd nerf this by making you spend a Warlock spell slot to cast the spell gained in this way, because as is, you can take one level in this class and then just combine it with any other spellcaster for access to every 9th level spell and below. The 6th level feature needs clarification, because I don't know how to expend my Gen Die, which gets smaller as you level up (this makes sense, I swear). The 10th level feature is Boring But Practical, and the 14th level feature turns you INTO A GENIE. INFINITE COSMIC POWER.... ittybittylivingspace. For 1 minute, anyways.
SCHOOL OF THE BEGUILER: LIKED IT. This is a Wizard that is meant to be 1/3rd Rogue. So, an Inverse Arcane Trickster. It looks like loads of fun, and might be a good model for other class-hybrid wizards in the future!
SCHOOL OF THE MAGE HUNTER: LOVED IT. This Wizard takes the model of Bladesinging and inverts it to give other creatures trouble against you. Think of a Hexblade Warlock designed to fight mages and planar entities and you have a good start. Absolutely a good class to pit your PCs against if the party's Beguiler has been causing too much mischief.
SCHOOL OF RECONSTRUCTION: LIKED IT. This wizard is an alternate Evocation wizard who can heal instead of gaining bonuses to damage. They get Sculpt Spells at 10th level instead of 2nd to make up for it, which lets them heal allies they choose to save. That's really all there is to it.
BACKGROUNDS: LOVED IT. Each of the backgrounds is thought out to the same level of detail as the ones in the Player's Handbook, and are great for common backstories for players and NPCs alike. I'd change the Dead's feature, however, as it currently relies on Downtime- a feature many campaigns fail to take advantage of.
FEYBLOOD RACE: NEEDS LOTS OF WORK. Implied to be Half-Fey, making them closer to Aasimar than Tieflings. Racial statistics are a mess and need complete revision before I'd even think about using them. They gain advantage against being charmed from two features. They gain the Dryad's Fey Charm ability, but since it was directly copied and pasted without regards to context, this gives the Feyblood the ability to charm every humanoid and beast that gets within 30 ft. of them. for an infinite duration with no action required, an infinite amount of times. Also, getting spells at 3rd and 6th level just seems weird compared to the precedent set by every other race Wizards has put out.
OPTIONAL RULES: LIKED IT. There's not much to say here. If you're the type to use these optional rules, they're a decent resource. They aren't particularly inspiring or masterful on their own. I do enjoy the crit-fail table results that have you "missing" so hard that you stab reality. I'm not sure what the Corruption Levels are used for or even what they mean, so I'm ignoring them for now until they are either removed entirely or expanded upon.
MAGICAL ITEMS: LOVED IT. These items are all very creative. I might label some of the uncommon ones as common, however.
ADVENTURE: LOVED IT. A mini-campaign that takes PCs from level 1 to 3 in Port Nyanzaru. It does not necessarily connect to Tomb of Annihilation, but it takes place in Chult all the same- instead, the players are pitted against the Xanathar's minions. This adventure is, for the large part, the same quality you would normally expect out of Wizards of the Coast, and makes great use of existing NPCs, varied statblocks, and interesting encounters and mechanics to liven things up at every turn. There are some errors, however, such as describing a pair of sailors as playing cards one paragraph and then as being asleep the next. ....so it's the same quality you would normally expect out of Wizards of the Coast.
MONSTERS: LOVED IT. Urban dryads can add a lot of flavor to an urban campaign, especially if your party has an urban druid or an urban ranger (such as the Burghal Explorer published in this book). Gen are not limited solely to being a warlock's familiar, and can add a lot of flavor to any campaign that makes use of genies and elementals in general. I have minor concerns over the spells the Gen can cast once they actually become your familiar, but they're not as strong as the spells you yourself should be casting at that point.
....urban, urban, urban, urban....
ART: LIKED IT. A lot of the art is recycled from Wizards of the Coast books, but that's okay since they're generally used to great effect. The art that is new to the book only stands out a little in comparison, so it's pretty high quality. The Xanathar's asides are pretty good too.
PRICE: WORTH IT. This book is every bit as quality as a Wizards of the Coast book... that hasn't quite finished the revision process. It's a little pricey for the amount of content you get compared to other digital D&D books, but dang is it good content, and hey, I'm glad to support fellow Dungeon Masters.