Before beginning this review, I would like to thank Ariadne’s Codex of Strings LLC for providing us with a digital copy of The City of Mirrors. This D&D5e-compatible adventure spans approximately 160 pages and is set in the mad dimension of Carcosa, the realm of the King in Yellow.

If you decide to buy it after reading this review, you can purchase a digital copy directly from the publisher’s store for £29.99 — around €30.

The adventure module is designed for 3 to 5 players with characters at level 14 or above, and is part of the wider Codex of Strings project. This game universe has its own SRD, which can be downloaded for free directly from the authors’ website. Codex of Strings (CoS) is an ever-expanding series of modules featuring new game settings, monsters, items and player options. The universe is coherent: each published volume is part of the larger CoS setting and compatible with the others. While the supplements can be played individually without reading the others, you may miss references to NPCs or previous situations. To fully appreciate The City of Mirrors, we recommend reading Ariadne’s System Reference Document at the very least.

If You Wanted to Start from the Beginning

As I was saying, although this volume can be read independently, it makes several references to the wider project. If you don’t want to miss any details, you should know that The City of Mirrors is the sequel to three other books:

• The Ichorous Peninsula: exploring the origins of the corruption of the King in Yellow. The abominable creatures described in the manual are the direct result of Hastur’s interference with the powers of Asgard.
• In Allfather’s Ink, the events culminate in Odin’s defeat, and three characters who also appear in this storyline are introduced: Shefus, Char, and Stormwalker Geld.
• The Court of the Afterlife delves (obviously) into the Afterlife of this game universe, focusing on Stormwalker Geld, who fulfils his duties as the elected representative of a ruined Asgard.

Although the manual provides enough information to enjoy the adventure without having played the other stories, you may still be curious to discover the other volumes of the Codex of Strings.

The City of Mirrors: the Premises

The introduction to the volume is about ten pages long and sets the scene for the adventure. We learn how Hastur has sown madness and chaos in previous volumes, leading several non-player characters (NPCs) from the setting to hunt him down. The same three NPCs are presented in such a way that the GM can modify and integrate them into their own plot, if desired. They are important recurring figures that the characters must take into account as the story unfolds because they accompany them.

Let us discover Shefus the Undauted, Red Char the Corsair, and Stormwalker Geld together with his trusty steed Umbra. They are all described in detail, with precise profiles accompanied by descriptions of their relationships with each other.

The City of Mirrors cannot be accessed without a guide to lead the expedition. Consider also that the winding paths of the cosmos become exponentially more dangerous the further one strays from the light of the Great Tree. Therefore, the adventurers will accompany Geld in his attempt to stop Hastur.

Chambers’ Work on Loan for D&D5e

The figure of Hastur, the King in Yellow, first appears in literature in Robert W. Chambers’ eponymous collection. Consisting of ten short stories, it is a perfect example of gothic literature and was a source of inspiration for H. P. Lovecraft, among others. Hastur iconically represents madness and alienation, and is more commonly associated with horror narrative games than with the world’s best-known roleplaying game.

Therefore, it may seem forced to focus on this figure, which is iconically untouchable due to its overwhelming nature and connection to the psyche, in an adventure based on a system of numerical statistics in which the characters are powerful heroes. After all, a key feature of gothic horror literature is the sense of powerlessness in the face of mystical and cosmic elements.

Structure of the Work

As always, we do our best to avoid spoilers when presenting adventures. However, it is helpful to have an idea of how the story is structured and what will happen to the characters as it progresses.

This story is divided into three main sections, each marking a different part of the adventure.

The beginning is located beyond the Void, in the City of Mirrors, the domain of the Yellow King. The heroes reach it with the NPCs thanks to Bifrost reopening. Yes, we’re talking about the rainbow bridge from Norse mythology. However, to reach the city itself, they must cross the Glittering Paths of Reflection, a labyrinthine set of ruins atop large mirror fragments leading to Carcosa.

The second part of the adventure is set in the city of Carcosa. Here, the challenges become truly daunting. It is a labyrinthine demiplane: a chaotic maze of a thousand streets and dark corners filled with incredibly tall buildings and monstrous, almost organic towers that intertwine and wrap around each other. Gravity itself becomes an obstacle here, allowing visitors to walk along ceilings and walls at random, much like in an Escher painting.

In the third and final part of the adventure, adventurers will find themselves on the shores of Lake Hali, where the Pale Throne awaits them. Stormwalker Geld and his companions must battle their way through the Mad Court nobles, from the Weavers to the Princes, until they confront the Yellow King himself.

A Bestiary of All Respect

The City of Mirrors is filled with encounters with crazy and dangerous creatures. For this reason the book ends with a 20-page bestiary. Each creature is accompanied by a striking image and a detailed description of its abilities, powers, actions and bonus actions. The difficulty, emotions and revelations build to a crescendo.

From this perspective, the authors have indulged their imagination, creating a carousel of increasingly peculiar and dangerous beings. It is worth delving into the plot, if only to encounter the King in Yellow. However, the creatures I found most interesting are undoubtedly the Hounds of Hali. These hounds can move from the material plane to the ethereal plane and vice versa with their bonus action. Another fascinating creature is the Tattermask Harlequin, which does not provoke attacks of opportunity when moving in and out of other creatures’ areas.

Review of The City of Mirrors‘ Aesthetic

One of this module’s undoubted strengths is its graphics. First and foremost is the majestic cover, created by Matias Lazaro. The text is accompanied by the works of Nacho Lazaro, Kim Diaz Holm and Midnight, who skilfully depict disturbing elements and create charming and tense NPCs.

It is definitely an enjoyable product to browse through, even in its digital version. The layout follows the standard used in the original editorial line, with a clear font and important elements in italics. There are clearly visible boxes for DM notes throughout the volume, and the opponent tables are rich and easy to use. The index at the beginning of the book is detailed yet concise. It also allows for precise navigation thanks to useful hyperlinks. In short, it is a very well-made product.

Carcosa first appears in Ambrose Bierce‘s work as a city of tall buildings, described vaguely and retrospectively by one of its inhabitants. In the works of Chambers and Lovecraft, the city becomes the realm of Hastur. It is a mysterious and ancient place, perhaps cursed, on the shores of Lake Hali, situated either on another planet or in another universe.

In The City of Mirrors, Carcosa is described as the castle from which Marduk and Tiamat ruled the lower planes. Now, under Hastur’s dominion, it has become a floating realm filled with unstable, mirror-like formations and dark, warped reflections.

Conclusions of the Review of The City of Mirrors

In conclusion, I can confirm that The City of Mirrors is an aesthetically pleasing product. It will certainly provide your gaming group with many hours of entertainment. Personally, I don’t like the idea of a group of powerful NPCs supporting the player characters. There is a risk that you will end up with a deus ex machina that resolves the most difficult situations. It’s a strange safety net, especially since this adventure is difficult.

This is not a book for everyone. It deliberately combines multiple sources and traditions in an attempt to present the best aspects of each. While it does not always succeed, it provides a series of excellent ideas that can be reused in other contexts. The overall effect is harmonious, creating the impression of a relentless climb where oxygen is occasionally scarce. This book is not an adventure for novice game masters: there are too many references to manage, and the increasing difficulties are hard to balance, partly due to the cumbersome presence of NPCs.

If you love challenging storylines packed with difficult encounters and appreciate the wide range of references they draw on, then The City of Mirrors is the adventure for you!

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