Spell Spotlight: Forbiddance
Forbiddance is a spell in the Player’s Handbook that I doubt most Dungeons & Dragons players have ever heard of, let alone cast. This Spell Spotlight is the story of how one spell utterly broke an adventure I wrote and had published in the D&D Adventurer’s League, and how I managed to fix it.
What Does Forbiddance Do?
Before we get into this story, we need to make it clear what forbiddance can actually do. It’s a fairly innocuous spell at first glance. By spending 10 minutes to cast this 6th-level spell, you can ward up to 40,000 square feet of floor space against planar travel, and against a specific type of supernatural creature—celestials, elementals, fey, fiends, or undead. It also lasts 24 hours, and can be made permanent (until dispelled) by casting it every day for 30 days.
Essentially, forbiddance is a spell with a very specific function: to protect an area, generally your home base or any other location you need to protect for a significant amount of time. It even lets you create a password, just in case you’re fighting against demons and need to let a devil ally inside the warded area. (Stranger things have happened in the Blood War!)
However, if you aren’t careful, this seemingly defensive spell can be turned into an incredible offensive force—one that can purge dungeons in mere moments.
Fire, Ash, and Ruin: Bug-Bombing a Dungeon
High-level play is hard to design for. The player characters have grown so powerful over the course of their adventuring career by 13th level or so that it’s hard to know what will actually challenge them anymore. This is true for home D&D games when you’re designing for players you’re familiar with, but it’s even more relevant to designers who are creating dungeons for 3 to 7 characters with unknown class combinations and a wide range of levels.
With that in mind, my first foray into high-level adventure design was a train wreck. I designed an adventure titled Fire, Ash, and Ruin for the seventh season of the D&D Adventurer’s League, which complemented the Tomb of Annihilation storyline. In this adventure, 3 to 7 player characters of 11 to 16th level ventured into the Land of Ash and Smoke, a region of Chult dominated by ash fields and active volcanoes. Within the Land of Ash and Smoke was an abyssal void known as the Pit of Krahharu, a dungeon filled with demons and ruled by a balor—Immilor, Lord of Blue Flames.
I made a lot of rookie mistakes in this adventure, including everything from making the fights too easy to making sweeping assumptions about party composition. But taken on their own “merits,” no single mistake in Fire, Ash, and Ruin was as damning as failing to account for one spell: forbiddance.
The Pit of Krahharu’s dungeon level was a sprawling, labyrinthine complex filled with demons. Every single enemy in the dungeon was a fiend, from the lowliest minion to the dungeon’s commander: Immilor the balor. Maybe you can see the problem. By spending just 10 minutes of casting, a party with a cleric could cast forbiddance offensively, so long as they possessed the 1,000 gp material component. The spell would affect the entire dungeon with its 40,000 square-foot affected area, and by selecting fiends as the warded creature type, every single creature in the dungeon took 5d10 radiant damage every 6 seconds.
One cleric could just spend a 6th-level spell slot to fumigate the entire dungeon from the entrance. My poor demons never stood a chance.
I have to congratulate players who used this strategy for clever thinking. Using a defensive spell like forbiddance as a monstrously effective offensive tool is something I would applaud in my home games. In a home game, exploiting my errors is something I reward. Even at so great a scale, I would be happy that my players found a way to overwhelm my challenges. But that’s in a home game, a place where I can improvise new challenges on the fly in order to prevent a moment of triumph from becoming an anti-climax.
Published adventures are different. When this sort of error happens in a published adventure, it’s on other people to salvage an anti-climax themselves. Normally I’m happy to trust other DMs’ ingenuity, but in the Adventurer’s League, where strict rules-adherence is the norm and wild, frantic improvisation is a bug, not a feature? This sort of glitch doesn’t fly in that environment.
Fire, Ash, and Ruin v1.1: Saving a Disastrous Dungeon
Fire, Ash, and Ruin released to dismal reviews, but I fortunately had the chance to collect dozens of players’ feedback and create a revised version with its major glitches fixed. Some of these fixes were as simple as cutting mediocre content (like the boring wilderness exploration section at the beginning), while others were as complex as rewriting entire encounters.
Beyond simple fixes and complex fixes, however, is the elegant solution. In layman’s terms, an elegant solution is killing two (or three, or four) birds with one stone. In this situation, “an elegant solution” refers to solving a problem by using interactions already present within the game’s rules, rather than creating a new rule to fix a bug or an exploit. Game designers get high off of creating elegant solutions. It’s the game designer equivalent to the dopamine rush a player gets when their cleric kills every demon inside a dungeon by casting a single spell.
Suffice it to say, I’m proud of my solution to my forbiddance problem, and I hope my solution helps you with your own design. I solved it by creating a forbiddance of my own.
There’s a fairly innocuous line in the spell text of forbiddance. It reads: “The spell's area can't overlap with the area of another forbiddance spell.” It makes sense that the spells can’t overlap, otherwise a clever player or NPC could create an area of instant death (read, thousands of d10 worth of radiant damage per round) by stacking hundreds of castings of forbiddance in a single area.
I saved my dungeon from anti-fiend fumigation by proactively forbidding it against celestials. It’s thematic—a pit filled with demons wouldn’t want angels teleporting in and trashing the place—but more importantly, it prevents the player characters from forbidding the demons’ own lair against them, since separate castings of that spell can’t overlap.
Forbiddance in Your Game
I wasn’t even aware forbiddance existed when I wrote Fire, Ash, and Ruin. Lesson learned; if you can’t memorize every spell in the game, then playtest your adventures again and again and again. I hope you can learn from my mistakes—I did!
Characters who can cast forbiddance are rare; only clerics of 11th level or higher can cast this elusive spell. If you happen to be running a game with an 11th-level cleric, consider safeguarding your dungeons against offensive castings of forbiddance by:
- Proactively creating a forbiddance of your own, or
- Simply diversifying your enemy types.
Even in a demon-themed dungeon, I could have included enemies that weren’t fiends. Elementals corrupted by demonic power (which I included in the upper levels of the dungeon), crazed cultists, undead spawn of Orcus, mind-controlled illithids… the list goes on. Diversifying your monster roster protects against all sorts of spells and effects, not just forbiddance. It can make your dungeon stronger against a paladin’s Divine Smite, a cleric’s Turn Undead, a ranger’s Favored Enemy and Primeval Awareness, and all a dozen other traits.
Creating dungeons filled with diverse, yet still thematic enemies is a DM’s most elegant possible defense against spells that target entire groups of creatures like protection against evil and good and forbiddance. What other solutions have you come up with?
James Haeck is the lead writer for D&D Beyond, the co-author of the Critical Role Tal'Dorei Campaign Setting, and a freelance writer for Wizards of the Coast, the D&D Adventurers League, and Kobold Press. He lives in a five-room apartment/dungeon in Seattle, Washington with his partner Hannah and his two kitties—who are FORBIDDEN from jumping on the table!—Mei and Marzipan. You can usually find him wasting time on Twitter at @jamesjhaeck.