Eternia: The Ultimate Battleground Comes To Life! (1986)

Eternia is by some margin the largest playset produced in the vintage Masters of the Universe line. I don’t remember ever seeing it in stores back in the 1980s, and I didn’t know anyone who owned one. My only brief introduction to it was where it was referenced in one of the 1986 minicomics. Eternia is often compared to the G.I. Joe U.S.S. Flagg, a playset that was even larger and more expensive:

The Tampa Tribune, Nov 26, 1986

Design & Development

The initial designs for Eternia (called Mount Eternia at first) were done by Ted Mayer. In my interview with Ted, he said:

I was given the project to design a playset that would dwarf Grayskull. I just stood at my drawing board and started sketching. I remember for some reason that I wanted to do a big drawing. It came out at 40″ x 40″.

Early Eternia Playset design. Note the flying vehicle on top of this drawing. This was an early version of the Talon Fighter
This later update to the design features the Blasterhawk and Fright Fighter vehicles

Ted continued:

Everyone liked the design, and it was decided, by someone, to do a size mock-up. We started hacking foam and the result was the photo you can see on my website.

According to the Power and Honor Foundation Catalog, Mount Eternia was supposed to be located in the mountains between Castle Grayskull and Snake Mountain. Ted Mayer’s first version featured towers with three creature heads. Each head would open up to reveal a feature underneath – a gun turret, some falling boulders, or dripping slime.

The second concept featured a Grayskull Tower, a central tower with a wolf motif, and a volcano tower, The foam mockup changed the wolf motif to a demon motif; the final playset would feature a lion on the central tower.

Mike McKittrick was an engineer at Mattel who worked on the playset. A recent article at Pop Insider gets some background information from Mike:

“The Eternia Playset was a huge project and I was assigned to it as the lead engineer,” McKittrick recalls. “The project was so big in scope that my manager assigned two other engineers to assist me. At that time, MOTU had already peaked and overall sales were starting to decline. Marketing wanted something big to keep the momentum and increase sales.”

…“Not only was this set meant to be enormous, but it was also meant to expand by having the existing Castle Grayskull and Snake Mountain playsets attach to its sides for an even larger footprint,” McKittrick says.

According to McKittrick, the initial cost estimate was “through the roof,” and the company made its way through a list of more than 20 intended features in favor of replacing them with only a handful of features that were better. Still, the playset was extraordinarily elaborate and ended up with the highest tooling bill that Mattel had ever seen.

“I recall the original estimated production quota in round numbers was 60,000 units and break-even, I believe, was around 40,000,” McKittrick says. “As we progressed with final engineering and started making tools, the quota dipped down to around 40,000. As we approached the start date for production, the quota dropped to 20,000 plus or minus. Ultimately we produced a little more than 4,000 units.”

Image source: Pop Insider

According to an old interview with Ted Mayer on the Roast Gooble Dinner podcast (sadly, no longer available online), the sculptor working on the Central Tower was taking quite a while to finish the prototype. As a practical joke, a few of the others working on the project hid the unfinished prototype, made a quick rough sculpt copy of it, and then knocked the duplicate into the floor. When the sculptor came back into the room he thought his work had been destroyed!

Update 1: Sean Lehmkuhl recently shared some fascinating concept and prototype images that he got from a former Mattel employee. Below we see some fairly rough sculpted mockups, with a snake or reptilian face on the central tower. Also included are some flat Styrofoam stand-ins for the Fright Fighter and Blasterhawk:

Below we can see a further evolution of the design, with a more stylized face on the central tower and a more defined serpent tower to the right. It also appears to be significantly taller:

In the image below we start to see the final look for the central tower, with the lion motif and grabbing arms:

There was also a “blueprint” drawing by John Hollis, dated to June 19, 1985:

Many thanks to Sean Lehmkuhl for sharing!

Update 2: I had forgotten to add these “Mount Eternia” playset attributes from the excellent Power of Grayskull documentary. Among a lot of interesting features, it was also envisioned as having four towers at one point. It was also conceived as a fortress for the heroic warriors, rather than as a battleground for all factions to fight over.

Update 3: MOTU Joe has unearthed a number of concept drawings by John Hollis, who was the designer who took over the concept prior to its production. These images come from Heritage Auctions, where they were offered for sale in December 2023:

Playset & Packaging

The production Eternia playset was enormous. The Central Tower is over 30 inches tall. Three towers are included, along with Laser Blaster, weapons rack, the track, three vehicles and more. You can see the hand painted hard copy in the catalog images below. Also note that the Laser Blaster is gray rather than the red of the retail toy (Update: per Bryce W. the US version was red, but the version available in the UK was flat gray). The paint on the towers looks carefully airbrushed:

Image Source: Nathalie NHT

You can get a pretty clear idea of everything that’s included by looking at the parts list included in the instructions:

I don’t own an Eternia playset myself, however my friend and frequent contributor to the blog Øyvind Meisfjord has shared a number of videos and images to help give a clear picture of all of the features. To begin with, here is a picture of the playset, flanked by Castle Grayskull and Snake Mountain:

In the above image you get a feel for the playset’s size and also its ability to integrate with the existing major playsets via two connecting ramps.

Below is a nice view of the front of the playset, compete with background and Masters logo:

In the video below, we get a good look at the Grayskull Tower section of Eternia, and we can see how the prison gate can be made to close when the Jet Pak Fighter vehicle passes by on the monorail.

In the video below, we get a better look at the Viper Tower (which bears a closer resemblance to the Filmation Snake Mountain than the actual Snake Mountain Playset), and how the snake head can be rotated by reaching into the back of the tower:

One of the main features of the Central Tower is, of course, the lion mouth and claws. Working together, you can capture a figure, push away a figure, or capture and toss a figure away. Øyvind demonstrates using Tung Lashor as his victim:

The Central Tower features a Laser Blaster turret on top. However, the base can also accommodate the disc-shooting Blasterhawk vehicle, also released in 1986:

The base of the turret allows you to adjust the angle of the Laser Blaster so you can point in any direction:

Of course if you choose you can also display the included weapons rack at the top of the tower, too:

Moving down the back of the Central Tower, there are a few more features, including a working elevator and a movable Command Seat. There are four floors total:

The monorail coils around all three towers. Three separate vehicles can connect to the battery-powered Power Module, and each of the three vehicles has a different look and play pattern.

Battle Tram Vehicle:

Jet Pak Vehicle:

Sky Cage Vehicle:

Another look at the Eternia playset can be found on Pixel Dan’s channel:

The artwork for the packaging of Eternia was done by the late, great William George. There’s quite a lot going on in the battle scene on the front:

European version. Image source: Deimos

The three towers of Eternia stand between Castle Grayskull and Snake Mountain. Beast Man scales the central tower and Rattlor and Tung Lashor head toward the lion’s head entrance. Man-At-Arms fires the cannon at the top of the tower. Flying Fists He-Man and Terror Claws Skeletor do battle off to the side. A volcano erupts in the distance.

Battle Cat corners Stinkor at the Grayskull Tower, while several horde troopers rush up the outer stairs toward Snout Spout, who is dodging laser blasts from the Battle Tram. Rio Blast and Extendar stand at the top of Grayskull Tower, as the Fright Fighter flies by. Meanwhile, Moss Man drives Bashasaurus down the road from Castle Grayskull to Grayskull Tower.

Sy-Klone flies Blasterhawk near the summit of Viper Tower, and Megabeast rounds the corner at the base.

Here are shots of each side of the box from an old Hakes auction:

The playset also came with instructions and a very simple black and white comic called “The Eternia Story” intended to demonstrate the play features of the toy (note: Jukka Issakainen comments that it may have been illustrated by Bruce Timm):

Comics & Artwork

Eternia also came with its own minicomic: The Ultimate Battleground! In the story, King Hiss and Skeletor work together to raise the three towers of Eternia from beneath the ground. We learn that the towers, which predated both Castle Grayskull and Snake Mountain, had long ago been sunken beneath the ground by the Ancients. They feared that it would fall into the hands of their enemy, King Hiss. The story is more or less a means of introducing all of the playset’s features to the reader.

In The Search For Keldor, the presence of the three towers of Eternia allows the Sorceress to leave Grayskull in human form, and weakens the veil between dimensions:

In Enter… Buzz Saw Hordak, Hordak manages to enter the Central Tower. Initially it turns him good, but after he leaves the tower he finds that he has the power to shoot a buzz saw from his chest:

In Revenge of the Snake Men, King Hiss is able to use the power of Viper Tower to bring two Snake Men, Sssqueeze (called Tanglor here, an early concept name for the character) and Snake Face (previously known as Medusa Man, but not called by that name here), back from a nameless dimension:

In The Powers of Grayskull, The Legend Begins, He-Man and Sorceress travel back in time within the Central Tower to ancient Preternia, where they find the Snake Men, cybernetic dinosaurs and the three towers of Eternia:

The Eternia playset also shows up in a hidden picture puzzle featured in the Winter 1987 issue of the US Masters of the Universe Magazine:

The Eternia Playset features prominently in the 1986 Eternia poster by William George:

Eternia also appeared in a number of pieces of very fine poster art by Earl Norem:

Ultimately Eternia didn’t get into many fans’ hands. It was a huge playset and it would have taken up a lot of space at retail, which may have played into Mattel’s decision to make so few of them – well under the number they would need to even break even. The track became fragile with age, so it’s quite difficult to find an original that is still intact. It’s something of a white whale for MOTU collectors.

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Slime Pit: Evil pit of gruesome ooze (1986)

The Slime Pit was the second and final small playset released in the original Masters of the Universe toyline (the first was Point Dread, in 1983). Of all the playsets MOTU had to offer, the Slime Pit perhaps packed the most punch for its size. It was all centered around one play feature, but it what a feature!

Design & Development

The Slime Pit was designed by Ted Mayer, from an idea that came out of the boy’s design group’s many brain storming sessions.

In the above illustration, you can see many of the hallmarks of the final playset are in place, including the grabbing hand in the front, the hand around the side and the scroll design near the top. The slime-spewing head is wolf-like in this concept (a frequent theme in Ted’s designs, it seems), whereas the final version seems to have more of a dinosaur skull look.

Mattel more or less invented slime as a commercial product, and it has been a popular seller since the late 1970s. The Slime Pit was a clever way for Mattel to integrate its popular slime products into the world of Masters of the Universe.

Pixel Dan has done some extensive research on the history of slime. Take a moment to check it out in this video:

There is also some great information about slime in this article at Plaid Stallions and again in this piece by Dinosaur Dracula.

Production Playset

The final play set has a deeper pit area than the concept version. The paint applications are fairly simple, but it does have some well executed red and gray overspray on the gray stone areas and some brown overspray on the skull. These seem more well thought-out than the often haphazard looking paint applications given to the exterior of Castle Grayskull (particular later releases of the playset). Like the Fright Zone, the Slime Pit is adorned with Hordak’s visage (Hordak seems really into branding his image on all things Horde). There is also a sculpted skull near the back wall.

The playset came with a can of Mattel’s Horde Slime. This particular slime mix was much runnier than the kind of slime typically found on toy store shelves today. It was also available for free, separate from the playset, with the purchase of two action figures.

That runniness made it work great for the purposes of sliming action figures, but it also made it hazardous to rugs and upholstery, not to mention any furry MOTU figures like Moss Man, Panthor and Grizzlor. For that reason, there were a few warnings given about what not to do with the slime, which were of course promptly ignored by many enterprising young mad scientists.

Some kids just want to watch the world burn. Image source:


The box art was painted by the late, great William George. Taking cues from the design of the playset itself, the scene is set in ancient Greco-Eternian ruins.


The Slime Pit came packed with Escape From the Slime Pit, which showcased the mini playset’s power to turn its victims into mindless slaves of the Horde. In the story, He-Man is slimed and is only restored to his right mind by exposure to brilliant light:


The Slime Pit appears in the She-Ra episode, “Loo-Kee’s Sweetie.” It doesn’t really look like the playset, but it does feature slime and a number of dinosaur-like bones. In the story, the Slime Pit saps its victims’ strength rather than turning them into zombie slaves. It’s easy to see why this less disturbing concept might be preferred for the purposes of an animated kids’ show.

Other Media

The Slime Pit was featured in the June 1986 edition of Masters of the Universe Magazine, as both the cover subject and as a poster by Earl Norem. The artwork features Buzz-Off as the victim and Flying Fists He-Man riding to the rescue on Battle Cat.

It also is the centerpiece in a Kid Stuff audio book called Prisoner In the Slime Pit:

Like the Slime itself, the Slime Pit was a concept that Mattel would revisit over and over again:

The Slime Pit was planned to be reissued in Mattel’s King Arthur toyline, but never came to be. Image source: Fabrizio Fernetti
200x MOTU Slime Pit. Image source: Lulu Berlu
Mattel’s Harry Potter Slime Chamber playset
Imaginext Ooze Pit, very closely modeled on the original Slime Pit.

Mark Taylor’s Castle Grayskull: Introduction (Guest Post)

Upper left: earliest concept art by Mark Taylor (before Mattel employment); lower left: black and white, and color version of the revised concept art by Mark Taylor (during Mattel employment in 1979); upper and lower right: the sculpted prototype by Mark Taylor)

Written by Dejan Dimitrovski

Envisioned and created by Mark Taylor Castle Grayskull is, both literally and metaphorically, the foundation stone of the world of the Masters of the Universe. Like an archetypal image, it has grown from a child’s toy to become an iconic symbol in both pop culture and in superhero mythology of our modern time.

Beginning, creation and original story idea

The concept of Castle Grayskull began with a fantasy drawing by Mark Taylor made even before he was employed in Mattel (sometime about 1975 – the picture on the upper left). Later, working as a toy designer in 1979., he did a revised castle illustration (the lower left picture). It went through many changes and revisions, again and again, until finally Mark sculpted the prototype castle (with a little help of Ted Mayer) based on the latest revised design (two images on the right show the prototype design). All through the design process, Mark insisted on the ancient, eldritch outlook of the Castle, invoking an atmosphere and image of a place that withholds secrets from beyond time and space, and setting it apart from yet another mythical magical castle.

“I wanted it to be organic, it has to look like it weights, like it’s heavy, has a lot of weight to it… like it’s starting to melt”, describes Mark Taylor during a panel on Grayskull Con in 2013.

The Castle was made before any of the toy figures and all through the eighties (and in some world countries the nineties), it undoubtedly became one of the most iconic, most popular and well known play-sets for children across the world. Starting from the original story concept, Castle Grayskull was the connection/conflict point of the hero He-Man and the villain Skeletor; and this concept was stretched to all the later incarnations of MOTU – the castle is always the ultimate fortress that Skeletor wants to conquer and claim its mystic powers. Another concept, started by Mark, that will remain a constant element common to all MOTU canons and story versions, is the concept that the ultimate Power is within Grayskull.

Inspiration sources and symbolism

Besides the idea of a traditional scary medieval castle, Mark mentions several other sources of inspiration for Castle Grayskull, among which are the works of Mark Twain, the 1933 “King Kong” movie (specifically the Skull Island), as well as other places that are skull-associated or shaped. Evidently, most of these inspiration sources seem to rely on the symbol of the skull. This symbol is as ancient and old as humanity itself, and it is a very complex one. Though the most common symbolic use of the skull is as a representation of death and mortality, to some ancient societies it is believed to have had the opposite association – objects like crystal skulls represent “life”, the honoring of humanity in the flesh and the embodiment of consciousness. Thus, it can be viewed as a symbol of extreme polarities of life and death.


Mark Taylor’s Castle Grayskull is a masterpiece that has outgrown the concept of a child’s toy; it served and still serves many purposes on many different levels.
At the time of the genesis of MOTU line, it was a big turning point for the brand. The Castle, together with wave one toys, not only set the specific mysterious feel of the MOTU setting, but was also crucial in the successful launching of the brand, as it became one of the most famous, most recognized play-sets for children across the globe.

From the perspective of Mark Taylor’s world of MOTU, it is one of the main elements that started the whole story. The Castle was where all the power lay for He-Man and Skeletor. Whoever controlled Castle Grayskull, had access to the Well of Souls and basically controlled all of the power.

Finally, in the terms of our modern mythology analysis, I believe it is a complex symbol that represents the battle for dominance of the forces of life (as well as hope and courage, represented by He-Man) and the forces of death (including fear and dread – incarnated as Skeletor) in an ever-present, ongoing struggle. This battle of life and death, survival and demise, creation and destruction, is set in our collective subconscious – a universal experience known to all of us; and it is always shrouded in mystery because it is always challenging and ever-changing, demanding our constant adaptation and creativity. This is how the myth of Castle Grayskull speaks to both the grown up and the child in us, allowing us to relate to the existential battle of the hero and the villain, a battle we have fought and will fight till the end of days.

* * *

I wish to express my gratitude to Rebecca Salari Taylor and Mark Taylor for being willing to help and to reveal and share the information on the original Castle Grayskull with us.
Also, I would like to express my thanks to my friends Jukka Issakainen and Adam McCombs in providing help and information in writing this post.


1. Grayskull Con. (Aug 6, 2013). “Grayskull Con 2013 – Panel Rebecca and Mark Taylor”. Retrieved from

2. Mark Taylor audio interview (including transcripts) conducted by conducted by Matt Jozwiak (around 2006.)

3. McCombs, A. (2015). Battle Ram: A He-Man blog. [Blog] Castle Grayskull – Fortress of mystery and power (1982); Available at:


MOTU Classics Castle Grayskull

MOTU Classics Castle Grayskull box art, by Rudy Obrero

Masters of the Universe Classics Castle Grayskull, released in December of 2013, was quite an achievement in an era when big playsets are becoming rarer and rarer. Larger, more complex and more detailed than the original, Classics Castle Grayskull was offered for a preorder price of $250 – more than three times the inflation-adjusted cost of the original, but still not bad given the size, complexity, and lower number of units produced.

Source Material

MOTU Classics Castle Grayskull’s biggest single influence is the original prototype playset sculpted by Mark Taylor in 1981, although the Classics version is somewhat tamer and less decrepit looking.  Some of this influence is no doubt filtered through the cross sell artwork and minicomic depictions by Alfredo Alcala (both based on the prototype).  Other influences include some invented details from Alfredo Alcala’s artwork, the original, vintage Castle Grayskull playset, the original Rudy Obero box art, and a concept Dungeon playset designed by Ted Mayer.

The large weapons rack on the right was sold separately from the castle. The manhole cover and the triangular weapons rack are third party customs, by BadVermin and Barbarossa, respectively

Throne room. The purple banner on the left was invented for this castle – the one on the right based on the vintage castle’s banner.

Concept-inspired computer and jet pack

Dungeon  section of the castle, with manacles and vintage toy inspired sticker

Classics Grayskull came with this orb stand (but not the marble sitting in it). It hides away in the secret orb room, inset behind the helmet of the castle

The Spirit of Grayskull haunts the throne room.

Castle Grayskullman guards the dungeon.

Secret door above the ledge

Into the throne room

Scare Glow, produced several years before MOTU Classics Castle Grayskull, came with a secret key to Castle Grayskull.

Scare Glow’s key fits into a keyhole on the secret side door, providing enough leverage to open the door.
He-Man stands on the open jaw bridge. The jaw bridge opens by inserting the power sword into the small opening to the right – a nod to the vintage minicomics.

The evil warriors sneak around the back.

Clawful climbs the scaling ladder

Here’s a more detailed breakout of the influences that went into creating the Masters of the Universe Classics Castle Grayskull:

Material taken from the vintage prototype or vintage concept art includes:

  • Ledge on the left tower
  • “Pawn” piece on top of the helmet
  • Taller helmet and battlements
  • Eye shape
  • Removable handle in the side allows for concept Castle’s side battlements
  • Throne design
  • Computer design
  • Skull motif at top of elevator
  • Hidden side door
  • Battle Tester
  • Jetpack
  • Manacles
Original 1981 prototype Castle Grayskull, by Mark Taylor. Image source: The Power and the Honor Foundation
Original 1981 prototype Castle Grayskull, by Mark Taylor. Image source: The Power and the Honor Foundation
Another copy of the vintage prototype. Photo courtesy of Andy Youssi.
Mark Taylor’s concept for the “Battle Tester”. Image source: The Power and the Honor Foundation

Material taken from the vintage playset:

  • Elevator design
  • Flag design
  • Ladder and laser blaster design
  • Banner, trap door and dungeon grate decals
  • Drawbridge design, front and back
  • Handle on the side piece (removable)
Image source: Transformerland

Vintage box art material:

  • Nose shape
  • Elongated fangs
  • Enlarged lower teeth
Vintage Castle Grayskull box art by Rudy Obrero

Minicomics material:

  • Third floor
  • Dungeon walls (window and skull designs from Ted Mayer’s dungeon playset)
  • Secret slot to gain entrance to Castle located to the side of the jaw bridge
From King of Castle Grayskull, illustrated by Alfredo Alcala
From King of Castle Grayskull, illustrated by Alfredo Alcala
From King of Castle Grayskull, illustrated by Alfredo Alcala
Ted Mayer’s dungeon playset. Image source: The Power and the Honor Foundation

There are several unique touches to the playset as well, including an additional secret door off the side of the throne room, a secret orb room in the back side of the helmet, and extended floor with plug for Wind Raider stand, and an “evil” throne room banner to match the original “good” one.

The original design for the Classics Castle Grayskull (artwork by Nate Baertsch, who is a frequent collaborator with the Four Horsemen) was to include a number of other goodies as well, including a clear “Spirit of Grayskull” display (from Alfredo Alcala’s artwork), a removable dungeon, a triangular weapons rack, a mechanism to open the secret door on the castle’s left tower, a sculpted dungeon grate, and a few other goodies. These seem to have been removed from the final product due to cost.

Image source: The Art of He-Man

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