When Manual of the Planes hit the shelves in 1987, it expanded the scope of Dungeons & Dragons in ways that made mere material plane adventurers feel positively mundane. Penned by the legendary Jeff Grubb, this book hurled players headfirst into the swirling chaos of interdimensional travel, answering burning questions like: “What happens if I step into a portal shimmering with eldritch energy?” (Spoiler: It’s rarely good news.)

A Leap into the Multiverse

Before Manual of the Planes, the cosmology of D&D was a loose and often contradictory patchwork. Bits and pieces about other dimensions had cropped up in The Dragon magazine and earlier rulebooks, but there had never been a single, definitive guide to reality bending adventures. TSR remedied that oversight with this tome, mapping out the multiverse in a way that would become foundational for D&D lore.

In classic first edition Advanced Dungeons & Dragons style, Manual of the Planes is a heady mix of Gygaxian prose, mathematical gravity calculations, and “your players will definitely die here” warnings. If you ever wanted to know the exact effects of elemental composition on spellcasting, congratulations you found your book.

The Great Wheel Cosmology

The Manual introduced what would become known as the Great Wheel cosmology, a framework that lasted for decades in D&D lore. The basic structure is this:

• The Prime Material Plane (where your classic fantasy adventures take place)
• The Inner Planes (fire, water, air, and earth, plus their many violent permutations)
• The Outer Planes (realms of gods, fiends, and celestial bureaucracies)
• The Ethereal Plane (misty and weird, but great for eavesdropping on reality)
• The Astral Plane (the expressway of the multiverse, where your soul might take an unexpected road trip)

This system gave a sense of order to the previously chaotic idea of different dimensions. It also gave Dungeon Masters an arsenal of terrifying places to send their players when they got too cocky.

Highlights from the Planes

The Inner Planes: Where Physics Goes to Die

The Inner Planes are the elemental foundations of reality, which sounds cool until you realize they are mostly uninhabitable death traps.

• The Plane of Fire? Eternal immolation.
• The Plane of Water? Hope you can hold your breath forever.
• The Plane of Earth? Just rock. Endless rock.
• The Plane of Air? A never ending freefall.

Jeff Grubb clearly had a vision: make sure no one assumes planar travel is a vacation. Yet, for all their hostility, the Inner Planes offer fascinating exploration opportunities, assuming your wizard packed the right spells.

The Outer Planes: Home of the Gods (and Their Petty Squabbles)

If the Inner Planes are primordial chaos, the Outer Planes are the spiritual battlegrounds of the multiverse. Each one embodies a particular philosophy or alignment, making them as much ideological realms as physical ones.

• The Nine Hells of Baator: Ruthless infernal bureaucracy with a side of fire and brimstone.
• The Abyss: If chaos had a headache and decided to create a thousand horrifying layers.
• Mount Celestia: Lawful good to the point where paladins probably get speeding tickets for flying too fast on their celestial mounts.

Each of these Outer Planes is a campaign setting unto itself. If you’ve ever wanted to argue semantics with a devil or attempt to rob a god, this is where you go.

The Astral and Ethereal Planes: The Weird Side of Reality

The Astral Plane is the ultimate liminal space literally. It’s where your mind drifts when you die, where githyanki ride around on red dragons, and where psychic combat is just another Tuesday. Meanwhile, the Ethereal Plane is a ghostly reflection of the Material Plane, useful for spying and phasing through walls (assuming nothing horrifying is lurking in the mist).

Why Manual of the Planes Mattered

While not a bestselling D&D book of its time, Manual of the Planes had a massive influence on later editions. The Planescape setting in Advanced Dungeons & Dragons 2E took these ideas and ran with them, turning planar travel into an entire campaign concept. Later editions kept refining the cosmology, but the bones of the Great Wheel still persist in D&D 5E.

For Dungeon Masters, Manual of the Planes was both an inspiration and a warning. It contained countless ideas for adventures, but it also reinforced that planar travel should not be taken lightly. One wrong portal and your party’s fighter might find himself in the Positive Energy Plane where he’ll glow brightly for a few moments before exploding.

Conclusion: To the Planes and Beyond

If you love D&D and haven’t flipped through Manual of the Planes, you owe yourself a peek. Sure, modern planar guides are more streamlined, but there’s something delightfully old school about the book’s dense descriptions and complex travel rules. It reminds us that the multiverse is vast, dangerous, and full of adventure, and that’s exactly how it should be.