The Eternal Boundary - Review

The Eternal Boundary, the first published module for the 2nd Edition AD&D Planescape campaign setting, I was lucky enough to get a physical copy from a friend as a gift and have enjoyed running it twice. First, using 5th Edition D&D rules and some home-brew planar race and faction options and the second time this last summer using the original 2nd edition ruleset as part of my Roll20 Great Modron March campaign. I’ve touched on the Eternal Boundary module before when I discussed using Perplexities as Hooks but wanted to do a full review.

As the inaugural Planescape module, aside from two brief single page adventure prompts in the setting boxed set, the Eternal Boundary does a fantastic job introducing some of the seedier areas of Sigil as well as the kriegstanz or undeclared war between the factions and the power of belief in the setting.

Spoilers for the Eternal Boundary Follow...



Much like Against the Cult of the Reptile God, the Eternal Boundary strength is how it can be run as a miniature sandbox. The party is tasked, either by a faction high-up or a mercenary recruiter, with looking into a macguffin, information about a demiplane known as the Isle of Black Trees. They’re told that an NPC wizard, Eliath, is barmy (crazy) but might know something and so the party is sent into the slums of the Hive ward to find him.

The module is broken down into three chapters: in the first the PCs get to explore the slums and dive bars Hive, looking for Eliath, getting a sense that something is not quite right, even by the chaotic standards of the ward, before discovering that Eliath was found dead and cremated (in the Elemental Plane of Fire, no less). In the second, the PCs are brought back by their employer and told that despite his reasonably well-supported death, Eliath has been seen alive and well in a Doomsguard bar wearing the colors of that faction and the party has a chance to begin unravelling the conspiracy that is abducting barmies, faking their death and sending them out of Sigil to be brainwashed as loyal faction members who would nonetheless turn on their allegiances at any moment when their handlers give the word. The final chapter is dedicated to the Party’s exploration of the conspiracy’s citadel on the Elemental Plane of Fire.

The first chapter has the meat of the adventure, with numerous NPCs, locations and events for the Party to encounter and interact with as they try to track down Eliath. The adventure does a fantastic job of guiding a DM through when (and if) to use encounters to draw the party further in as well as making the Hive feel like a living, breathing place. Additionally, the NPCs are distinctively memorable, though Mordrigaarz, the Xaositect, might give DMs who are less comfortable with improvising dialogue some difficulty given his use of the Xaositect babble that results in sample dialogue like:

“Barmies lost someone’s making. To find out why and who I am. When thrashed every berk have I in Hive, the cutter I seek thrashed I’ll have too.”

If you can get away with it, a site like: https://onlinerandomtools.com/shuffle-words can be a tool for a DM to more easily create the Xaositect word scramble.

The second chapter has been a bit of a slump for me, when I’ve run, as it centers around the PCs visiting the Mortuary, run by the Dustmen. It’s a little tricky to handle, as the portal the PCs ultimately need to use to get to the Elemental Plane of Fire is in the Mortuary, so the PCs might need to explore a little, but given the danger and legion of undead, the party would need to be extremely cautious, which might not suit some more impulsive players. To give a taste of the danger, the party has a chance to run into the Dustmen Factol himself, a 19th(!) level wizard and Lich…

The final chapter is dedicated to the Citadel of Fire, which provides an interesting little dungeon-style exploration, where again, caution is required and more impetuous PCs might quickly get the party into trouble. There are a few more potentially deadly encounters, a stone golem that the NPCs could activate if alerted to the party as well as just the potential for the PCs to be mobbed by a dozen adversaries if the alarm is raised. The Citadel fares better than the mortuary as a place to explore, however, as the PCs will be rewarded with some of the truths behind the mystery of the adventure and any treasure they obtain here will not result in them being hunted by vengeful undead (a possibility if the PCs somehow get some of the treasures from the Mortuary).

Recommendations for Running:

Despite the lackluster middle chapter, I’ve highly enjoyed running the adventure the two chances I’ve had. Adapting it to 5th edition is fairly easy, since a DM mostly needs to pick out the appropriate NPC stat blocks and adjust spells slightly, though a DM will need to remember that the potions  work significantly differently in the earlier edition where a potion of invisibility allowed a PC to "quaff a single gulp—equal to 1/8 of the contents of the container—to bestow invisibility for 3-6 turns" (30-60 minutes) and a flask of oil of elemental invulnerability "contains enough oil to coat one man-sized creature for eight days or eight individuals for one day."

So where NPCs would give the party Potions of Invisibility and Potions of Fire Resistance, they should consider giving additional potions to make up for the difference between the number of uses a 2e potion and a 5e potion provided. A DM might also consider giving out Potions of Invulnerability in place of the Potions of Fire Resistance.

For both 2nd and 5th Edition, I would recommend having PCs be 2nd level, as the adventure can quickly turn dangerous and that second level gives PCs just a little bit of extra lee-way they might need to survive.

Both times I’ve run the game in 3-4 sessions of 4-5 hours each, so planning on 12-20 hours depending on your group’s play style.

The Good

    • The module has a great introduction with a background, adventure summary and detailed DM notes for preparing the module for play and summaries of the major NPCs, groups and factions.
    • Chapter 1 is a whirlwind tour of the Hive of Sigil, with plenty of great NPCs, locations and events for a DM to utilize. It turns the slums of Sigil into a mini-sandbox for the party to explore as they try to track down Eliath.
    • There is a barebones but player/PC appropriate map of the Hive Ward that can help the player’s visualize the section of the city as they move about it.
    • There is a NPC master table, with the bare stats of most of the NPCs and Monsters the PCs will encounter, making it easy for a DM running it with 2nd Edition rules to find the stats they need and providing a handy list for a 5th edition DM to reference as they find appropriate 5e stat blocks.
    • The mystery of the module plot is engaging. As I’ve written elsewhere, it is perplexing in a good way and the unanswered questions that keep coming up have served to keep players interested and hooked both times I’ve run the game.
    • The module introduces several iconic Planescape ideas: the kriegstanz, hidden faction war, the power of belief, the wards of Sigil and even a little planar travel with the jaunt to the Elemental Plane of Fire.

The Bad

    • The module might not be suited to more impulsive players as there are multiple places where the party will only succeed if they are cautious.
    • There is the potential for the party to be captured by several different NPCs, the Shadowknave, Toranna the Gray or even the Factol of the Dustmen. While this lets the PCs “fail forward” to the final chapter in the Citadel of Fire, it has the potential to feel forced for the players or to fall back on the somewhat tired and frustrated trope of PCs being captured and needing to escape without having their equipment handy. The module doesn’t say where the PCs equipment would be if they are captured, but I put it in the guard area of the “Guest Quarters” so that the PCs only had to go without for one fight.

The Ugly

    • The Mortuary gets a full map and numbered room key, but it really is not a place the PCs should be exploring all that much. The PCs really just need to find out how Toranna opens the portal to the Elemental Plane of Fire and both times I’ve run, I’ve tried to nudge the PCs to be very cautious and keep exploration to a minimum.