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The Astromundi Cluster (2e)

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Far off the traveled paths of wildspace, a lone crystal sphere bobs in the phlogiston, waiting for unwary visitors greedy for adventure. This is the Astromundi Cluster, a setting easy to find...and nigh-impossible to escape.

Unique among the spheres, Clusterspace holds no planets - only thousands of asteroids that wander in a seemingly endless realm. Here Arcane, neogi, illithids and humans have learned to coexist in a semblance of peace to ensure their survival. But the carefully-wrought balance of power may change at any time, and heroes have to choose their allies and enemies carefully. Within the Cluster, there are no such fine guarantees as honor or trust between friends and foes.

The Astromundi Cluster accessory includes: A 32-page player's manual to the factions and features of Clusterspace. The Astrogator's Guide gives players all the information they need about the races and major asteroid clusters of the Shattered Sphere, life and culture in the Cluster, and new ship and weapon types.

A 64-page DM guide, Adventures in the Shattered Sphere, which reveals to the DUNGEON MASTER the secrets of the Astromundi Cluster, from the magically powerful Antilan Empire to the behind-the-scenes plots of the Arcane.

A 96-page DM book describing in full detail the most important asteroids and other features of the Cluster, its physical makeup and economy, and new magic and spells.

Two full-size maps illustrating the planetary orbits of the Cluster's celestial bodies, and schematic layouts of a feared crystal citadel and important trading post. Twenty-four cards filled with ship blueprints, important faction illustrations and descriptions, orbital maps, and more.

Product History

The Astromundi Cluster (1993), by Sam Witt, is the third and final boxed supplement for Spelljammer. It was published in July 1993.

Origins (I): Another Spelljammer Box. Throughout the '90s, TSR included boxed sets in most of their lines, publishing one or two a year. The Astromundi Cluster was the third such boxed supplement for Spelljammer (1989), following the ship-focused The Legend of Spelljammer (1991) and the rules-focused War Captain's Companion (1992). And, it was something new: a campaign-focused box.

Origins (II): A Different Take on Spelljammer. Though Spelljammer introduced a new, science-fantasy take on AD&D, it had never truly been a setting. The Legend of Spelljammer and SJR5: "Rock of Braal" (1992) did detail a famous ship and a famous locale, but that was it. It would have been like TSR trying to detail a more traditional setting solely on the basis of two cities … neither of which had a fixed locale!

There was a good reason for this: Spelljammer's main purpose was to act as a conduit between all of the other AD&D settings. Players were expected to spelljam across the crystal spheres, adventuring in the Realms, Greyhawk, or Krynn. If that was truly the basis of the Spelljammer setting, then little more was needed.

But it didn't allow the setting to live up to its true potential.

From this point of view, The Astromundi Cluster was basically a soft reboot of the Spelljammer line. It merged together the unique Spelljammer rules with an actual setting for a whole campaign worth of adventure. And it went further: by revealing this sphere as the origin of the mind flayers, it also suggested what a more self-contained Spelljammer campaign could have been: it could have been a multiverse full of worlds that revealed the origins of many different D&D races.

However, even the designers of The Astromundi Cluster knew how far removed this was from the Spelljammer core: they cut off the Astromundi Cluster from the rest of the crystal spheres, allowing no in-and-out privileges. Players could either play in the larger multiverse of Spelljammer or the smaller world of the Astromundi Cluster.

So, consider it a subcampaign, and a view of how the Spelljammer line could have gone.

Origins (III): The End of Spelljammer. The Astromundi Cluster might have been intended as a final gift to Spelljammer fans. If it was instead intended as a new direction for the line, it was too late. The Astromundi Cluster was the last publication for the Spelljammer line. It would soon be replaced by the Planescape Campaign Setting (1994).

Exploring the Crystal Spheres. The Astromundi Cluster details a new crystal sphere called Clusterspace. With a whole box worth of details, it's unsurprisingly the most detailed Spelljammer setting. There's info on factions and unique races as well as an extensive almanac of all the celestial bodies in the sphere.

Exploring the Great Wheel. Rather uniquely, The Astromundi Cluster deviates from the line's focus on crystal sphere associated with Prime Material Planes; it instead ties Clusterspace to the Great Wheel. Because "the barriers between the various planes are quite weak", entities from the Inner Planes are quite common in Clusterspace. In fact, lots of demons show up too …

Monsters of Note. The ties to the Great Wheel allows The Astromundi Cluster to bring in monsters not usually associated with Spelljammer. Thus a few greater tanar'ri make their Spelljammer debut after previously appearing in MC8: "Monstrous Compendium Outer Planes Appendix" (1991): the babau, the chasme, and nabassu.

However, it's the mind flayers who get the most notable attention, and that's because the Astromundi Cluster is claimed as their home. They're said to be mutant humans, who then evolved into the illithid species. However, this doesn't match the history of mind flayers found in other supplements. In fact, The Illithiad (1998) goes out of its way to decanonize it, saying: "other scholars have pointed out 'suspect' sections of the Astromundi Chronicles. For instance, other sources plainly list the entity called Lugribossk as a proxy of the illithid god Ilsensine. Also, no other source has ever mentioned an individual with the name lllithid; some fanciful storyteller must have created it from 'whole cloth.' Finally, the proposition that illithids are merely mutant humans seems a rather simple explanation for a host of contrary lore — the least of which is the fact that illithids are hermaphroditic amphibians, while humans are mammals. All in all, this author looks dismissively upon the Astromundi Chronicles' claim to explain illithid origins."

Future History. Though Spelljammer ended with The Astromundi Cluster, its spirit lived on, most notably in "Spelljammer: Shadow of the Spider Moon", a more serious reinvention of the setting for D&D 3e, found in Dungeon #92 / Polhedron #151 (May / June 2002). However, one can also find reflections of Spelljammer in other settings, such as the Astral Sea that's found in D&D 4e, as described in The Plane Above: Secrets of the Astral Sea (2010).

About the Creators. Witt is a freelance writer who began writing for TSR in 1993 with The Astromundi Cluster (1993) and DSM1: "Black Flames" (1993). He'd write just a handful of D&D supplements from 1993-1995.

About the Product Historian

The history of this product was researched and written by Shannon Appelcline, the editor-in-chief of RPGnet and the author of Designers & Dragons - a history of the roleplaying industry told one company at a time. Please feel free to mail corrections, comments, and additions to

We (Wizards) recognize that some of the legacy content available on this website does not reflect the values of the Dungeons & Dragons franchise today. Some older content may reflect ethnic, racial, and gender prejudice that were commonplace in American society at that time. These depictions were wrong then and are wrong today. This content is presented as it was originally created, because to do otherwise would be the same as claiming these prejudices never existed. Dungeons & Dragons teaches that diversity is a strength, and we strive to make our D&D products as welcoming and inclusive as possible. This part of our work will never end.

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File Last Updated:
December 26, 2016
This title was added to our catalog on December 27, 2016.