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The Plane Above: Secrets of the Astral Sea (4e)


Climb aboard an astral skiff and set sail for adventure!

On the Astral Sea, characters face off against angels, devils, githyanki, and even the gods and their exarchs while exploring dungeons, raiding astral galleons, and establishing themselves as demigods. This game supplement builds on the overview of the Astral Sea presented in the Manual of the Planes game supplement and explores the heavenly plane in greater detail. From the cavernous layers of Nine Hells to the dark dungeons of Tytherion, adventure awaits in every astral dominion and on the vast, uncharted sea that stretches between them.

This game supplement describes the Astral Sea and key locations throughout the plane. It also presents a multitude of new monsters, as well as adventure hooks, encounters, hazards, and everything Dungeon Masters need to make the Astral Sea a featured setting in their campaigns.

Product History

The Plane Above: Secrets of the Astral Sea (2010), by Rob Heinsoo with Ari Marmell, Eric Scott de Bie, Robin D. Laws, Matthew Sernett, and Rodney Thompson, is the second supplement to the 4e Manual of the Planes (2008). It was published in April 2010.

About the Cover. The cover to Secrets of the Astral Sea immediately shows how different the Astral Plane is in the World Axis. Rather than being a featureless gray mist, the Astral Plane now looks like something straight out of Spelljammer (1989).

The piratical star of the cover is a githyanki, one of the races spotlighted within.

Continuing the Manual of the Planes. Shortly after the release of D&D 4e (2008), Wizards published Manual of the Planes (2008), which overviewed the new World Axis cosmology. A year later, The Plane Below: Secrets of the Elemental Chaos (2009) looked at the lower half of the Axis in more detail. The Plane Above: Secrets of the Astral Sea then completed 4e's trilogy of Manuals of the Planes.

Expanding the World Axis. During the second edition AD&D era (1989-2000), two new settings went far beyond the traditional worlds of D&D play. Spelljammer (1989-1992) imagined a space between the worlds that was filled with magical ships, while Planescape (1994-1998) made the Inner and Outer Planes into playable settings. Secrets of the Astral Sea feels like the spiritual successor of those two classic settings.

4e's Manual of the Planes had previously detailed the Plane Above in 28 pages, including 6 pages on the Astral Sea and 22 pages on its many locales. Secrets of the Astral Sea expands that into a 160-page sourcebook. It begins with 26 pages describing the Astral Sea, which reveals it as a place for adventure, much like the old Crystal Spheres of Spelljammer. From shipboard encounters, to astral dungeons, it's all here — and all much more interesting than the Astral Plane of previous editions, which was a dull place of transit and little more.

However, the majority of the background material in Secrets of the Astral Sea focuses on a half-dozen "divine dominions" (and any number of "shattered dominions" and "motes"). These are the homes of the gods that filled the Outer Planes of D&D's classic Great Wheel cosmology.

The divine dominions that get the most attention are Arvandor, Celestia, Chernoggar, Hestavar,the Nine Hells (really, only the first layer of Avernus), and Tytherion. Together, they reveal how much the divine dominions changed from the Great Wheel to the World Axis. The Nine Hells are, of course, one of the oldest planes in the D&D cosmology, while Arandor is a variant of Arborea (formerly Olympus) and Celestia is a new version of Mt. Celestia (formerly the Seven Heavens). However, the other three divine realms are new. The list of shattered dominions includes a few other classic realms such as Carceri (formerly Tarterus) and Pandemonium, but many of the classics planes of the Great Wheel are gone entirely.

There's a reason for this planar reduction: the divine dominions no longer contain a hodge-podge of gods from across Earth's history. Instead, the World Axis focuses on D&D's unique deities — both classic gods and new ones that appeared with the release of D&D 4e. Thus, Arvandor doesn't even hint at its Olympian gods of old. Instead it's all about Corellon, Sehanine, and Lolth.

Secrets of the Astral Sea also contains a lot of detail on the Dawn War at the heart of the Astral Sea's history. This fight between the gods and the primordials was previously detailed in Divine Power (2009). Here, it gives the dominions of the Astral Sea an almost post-apocalyptic feel — which is a great basis for dungeon crawls, as Earthdawn (1993) proved years earlier.

Monsters of Note. Just like Secrets of the Elemental Chaos, this new sourcebook provides details on many notable races in the Plane Above.

  • Couatls are flying serpents based on Quetzalcóatl that debuted in Supplement III: Eldritch Wizardry (1976). One appeared in an adventure early on, as a major encounter in the South-American-themed "C1: The Hidden Shrine of Tamoachan" (1980), and they've returned in every core Monster Manual published for the D&D game.
  • Githyanki are the evil creation of author Charles Stross. They first appeared in White Dwarf #12 (April/May 1979), then returned in the Fiend Folio (1981). OP1: Tales of the Outer Planes (1988), which featured a Githyanki lair, marked their first major adventure. The Githyanki's most important appearance was probably in the Incursion storyline that ran through Dragon #309 (July 2003) and Dungeon #100 (July 2003); it featured lots of Githyanki background and their attempted invasion of the prime material plane.
  • Marut premiered in the original Manual of the Planes (1987) as the unliving servants of the death-god Rudra. In AD&D 2e days (1989-2000), they found a home in Mechanus and became the servants of many deities. They were expanded during the D&D 3e era (2000-2008) to become the inevitables, a race that includes six different species: anhydrut, kolyarut, marut, quarut, varakhut, and zelekhut. The inevitables' full ecology appeared in Dragon #341 (March 2006), which now described them as "implacable agents of law".
  • Quom are a new race for D&D 4e. They seek to rebuild their civilization, destroyed in the Dawn War.

Secrets of the Astral Sea also includes monstrous writeups of several more races — particularly the devils, who were increasingly distinguished from demons in D&D 4e.

Future History. Secrets of the Astral Sea was the last of the hardcover Planar books for D&D 4e. It was followed by The Shadowfell: Gloomwrought and Beyond (2011), which appeared in a different format during D&D 4e's later (and less regular) period of publication.

About the Creators. Heinsoo, the lead design for D&D 4e, was also the lead author of this final planar manual. He'd previously coauthored the 4e Manual of the Planes (2008) that got it all started. This was Heinsoo's last book for D&D.

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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RJ R January 20, 2023 3:21 am UTC
Was this taken off POD? I was looking at it as a POD before and its still in my cart as a POD softcover, but I notice that option is no longer on this page. Not sure if I should still try to purchase as softcover or not.
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Timothy B September 15, 2017 6:57 pm UTC
This PDF is usually $7.99 on DM's Guild. The September Settings sale has actually increased the price to 33% off of the printed book's cover price, which is higher than the typical PDF price. Is there any way to get this corrected? Thank you.
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