D&D 5E What houserules would best support my campaign premise?

[Grantypants]

I had an idea for what seems like a cool campaign, but I think I'd need to tweak the 5e rules a bit to make it work.

The party would be all magic-users of some kind or another, and they've teamed up to find out why certain spells have stopped working. Turns out there's a BBEG who hates magic. He's found a ritual that can make a particular spell impossible for anyone to ever cast again. The party is travelling the world trying to find this guy, but also to find new spells to replace the ones they can't cast any longer. The main gameplay loop is finding loot in the form of spells, then using those spells until they stop working, rinse, repeat.

All the PCs have to pick classes capable of casting spells, at least by level 3, where we'll start. Artificers and psionic classes are not included as options, but are likely to show up as major antagonists. The PCs can only choose from PHB spells (or maybe even only SRD spells) to start with, but spells from all kinds of other sources will show up eventually. How much would it break if I just said that, for purposes of learning and preparing spells, everyone is wizards? Classes that previously limited the number of spells a character knows now just limit the number of spells that can be prepared?
Everyone gets the equivalent of a wizard's spellbook and has to prepare spells from their list of spells known, but also can copy spells into their spellbooks when they find spells in play. Since it will be a major focus of the story, I think I'd want to make copying spells much cheaper and faster than what is currently available.

Players will be encouraged to reskin their spellbooks into something more suitable for their character, but I'll leave that in their hands. Based on what they respond with, I'll also reskin spell scrolls and the like to match. Since I'm going to be ruthless in taking spells away, I also have to be generous in doling out new spells to keep the game fair, so new spells should be reasonably common in game.

What else do I need to consider?

I'll use a random table for selecting the spells that are deleted from the world. There's a few warlock invocations that refer specifically to eldritch blast, so I might open those up to benefit any warlock cantrip, in case eldritch blast is deleted. Other class features that refer to particular spells might be changed the same way.

 

[Quickleaf]

"Things go wrong" is never as compelling as how things go wrong.

That's why "hard counters" deployed against player character (e.g. counterspell, an area of dead magic, Turn Immunity) are usually less interesting than "soft counters" which tend to follow a "yes, but..." formula. My experience is that "hard counters" really need to be used judiciously to preserve the player's fun; in other words, they can easily be overdone.

Of course, with different GM styles and different players YMMV, but I see that as a weakness in the play loop you're describing. "Your fireball fizzles, nothing happens" might be interesting as a novelty... once... maaaybe twice if you're clever with it. But it's kind of...it kind of sucks, right? Why exactly is this happening? Where was the foreshadowing? Could it have at least gone out with a bang rather than a whimper?

As a player, when you tell me something goes wrong with my fireball spell... I'm leaning in and kind of perversely excited to find out how it goes wrong. I think the other (related) issue you might encounter is that "nothing happens" is something players really don't want to hear – unless you're in an investigation play loop where they're trying a bunch of things to see what sticks. But generally not in combat or high-conflict scenes. Too much "nothing happens" really kills the pacing.

 

[Aging Bard]

Quickleaf's point about How is really great.

I realize this is probably not want you were thinking, but my 1e mind looks at this setup and it is screaming "Henchmen!" I'd be hiring level 1-2 fighters and the like to accompany the main party. As henchmen, they are under the command of the PCs, though their morale could falter in stressed situations. As NPCs, their possible death is less personal to the PCs. Make some magic items useful to fighters discoverable and useable as payment.

Relatedly, I've seen lots of commentary about "weird" party compositions (e.g. all bards) and whether they are viable. If testing that viability is the point, fine. But if the players really want to play this way, henchmen are how to fill out the complete party.

 

[timbannock]

House ruling clerics into wizards is the simplest solution ever: replace spell book with prayer book and have it work the exact same.

Sorcerers and Warlocks might simply be "burdened" with a requirement that they interact with a spell once before they can ever learn it: either witness it take effect, be targeted by it, or read it in some form (including a spell scroll, which is a functional way to do all three potentially).

 

[Grantypants]

Of course, with different GM styles and different players YMMV, but I see that as a weakness in the play loop you're describing. "Your fireball fizzles, nothing happens" might be interesting as a novelty... once... maaaybe twice if you're clever with it. But it's kind of...it kind of sucks, right? Why exactly is this happening? Where was the foreshadowing? Could it have at least gone out with a bang rather than a whimper?

That's a good point. I should have made my assumptions clearer in my original post. In the morning when players are preparing spells, that's when they find out what spells are no longer viable options. This would not be something that they discover mid-combat. There might be a rare boss or something that adapts to spells borg-style after being hit once, but that would be the exception and not the rule.

 

[robus]

Hmm how about the wizards can see spells growing fainter in their spellbooks? The wizards could make a check (the DC getting harder the fainter it gets) to read the faint writing? That would nicely foreshadow things and cause a sense of urgency? Seems like lower level spells would go first as they’re the easiest to neutralize?

However I can also see this gimmick growing old rather quickly? Perhaps a level or two? But a whole campaign on this clock…?

 

[Quickleaf]

That's a good point. I should have made my assumptions clearer in my original post. In the morning when players are preparing spells, that's when they find out what spells are no longer viable options. This would not be something that they discover mid-combat. There might be a rare boss or something that adapts to spells borg-style after being hit once, but that would be the exception and not the rule.

Well, that's even less interesting, right? As flawed as the former condition was – i.e. losing access mid-encounter – the way you intend to run it removes even more element of discovery.

Before taking this idea into play, I would encourage you to think about it from the perspective of your players and the narrative first.

Right now, you're approaching it from a very top-down stance. World state changes. Meta-game, you inform players during spell prep, "no, fireball and tiny hut are no longer available to be prepared." Ok... as a player, that would feel like a really unsatisfactory explanation.

What does spell preparation look like in your game? What happens narratively when I try to prepare my fireball? For example, "the threads of the spell pull from your mind, like forgetting the voice of a long-lost loved one, and before your very eyes the very ink on your spellbook pages starts to bleed away" has vast story-telling implications. From a player's perspective, that narrative gets their wheels turning, "Huh, ok, so how could we preserve the knowledge of a spell? Like is there a monster with infallible memory that we could teach it to, and then go back to whenever we need to relearn the spell?" Or: "What if I chiseled my spellbook into rock?"

Again, that gets back to the hard counter idea. With a hard counter, there's no more room for discovery, the conclusion is foregone, and there's nothing for players to interact with. It's a very, very strong move of all the moves a DM could take. It's like partner dancing and suddenly you're busting out nothing but power moves and your partner has nothing left to do. A few power moves used judiciously, yeah, that can be a nice spice. But too much ruins the recipe.

Anyhow, this is all my opinion, and YMMV depending on play style.

 

[Grantypants]

Right now, you're approaching it from a very top-down stance. World state changes. Meta-game, you inform players during spell prep, "no, fireball and tiny hut are no longer available to be prepared." Ok... as a player, that would feel like a really unsatisfactory explanation.

There's no question that this premise requires a very particular sort of play style, both from the players and the DM. The players have to be willing to be flexible and recognize that the spells they have are temporary assets. The DM, meanwhile, has to make sure that the players continue to have options before they face a hard counter.

So yeah, they might not be able to prepare fireball or tiny hut, but last session they found chains of perdition and gloomwrought barrier and salt lash and song of the forest. The discovery aspect is meant to be "what are these new spells and how can I use them to accomplish my goals?"

The DM has a lot of work to make sure that the party does have the opportunity to find new spells as treasure over the course of the game. That's an aspect of treasure hunting that doesn't get a lot of support (in my experience) so I wonder what it would look like as a major pillar of a campaign.

You are right on the money as far as needing better narrative support for what this mechanic looks like to the PCs. That's something I want to brainstorm more.

I realize this is probably not want you were thinking, but my 1e mind looks at this setup and it is screaming "Henchmen!"

I hadn't really considered henchmen as an option. Since paladins and druids and eldritch knights and arcane tricksters would all be on offer, all the party roles could still be filled. But henchmen are the perfect backstop to make sure that bad party composition doesn't cause much of a problem.

 

[Neonchameleon]

All the PCs have to pick classes capable of casting spells, at least by level 3, where we'll start. Artificers and psionic classes are not included as options, but are likely to show up as major antagonists.

Um... in 5e there are no psionic classes? The closest to psionic classes are the subclasses of the Psychic Warrior Fighter, Soulknife Rogue, and Aberrant Mind Sorcerer.

Artificers are spellcasters, so why ban them?

I'll use a random table for selecting the spells that are deleted from the world. There's a few warlock invocations that refer specifically to eldritch blast, so I might open those up to benefit any warlock cantrip, in case eldritch blast is deleted.

Eldritch Blast is effectively a class feature of warlocks and Eldritch Blast + Agonizing Blast is how warlocks keep up in DPR. It might be worth just leaving it (and possibly a couple of healing spells) off the table

 

[aco175]

I was thinking that there would be problems between the main casters. Wizards have the most spells, so the most to loose. They keep the spells in their mind from the book until they study a new one. What happens when that spell goes bad. Do they simply forget it, like it never existed, or slowly over time. If their book looses it and they can keep it in their mind, maybe for a time. This is like sorcerers with all the spells in their mind. With little spells, how they loose the spells makes a bid difference. Warlocks get other spell-like powers, but are these spells for this purpose?

What about signature cantrips like Eldritch Blast. How are players to take it when these spells leave.

I wonder if there are items that cast spells like wands and staffs that recharge that the PCs can get. Not sure if these should keep the spells longer or until they run out. Maybe they only recharge 1d4 after a while or the max charge slowly looses one each week or such. scrolls and potions that keep the spell where it disappears from books, or these spells loose the spell as well?