How would you allow a higher level spell to be cast?

[Xapi]

Ok, so here's the thing. I'm running a "low magic" campaign, in that the setting has extremely few characters over lvl 12, and NONE over level 15. Magic items are likewise increasingly rare, specially the higher tiers.

Thirty years before the campaign starts, a band of adventurers is hired to kill the last living dragon. When they arrive at it's lair, and after killing this dragon, they realize he has a partner and a wirmling. At this point part of the party wants to continue on and eliminate them, while the rest are unwilling to commit what could be construed as genocide, and in the ensuing chaos, the mother and wirmling escape. The mother also has a fecundated egg about to be laid, wich is not known by the adventurers.

Now, thirty years later, the campaign's BBEG is one of those adventurers, a female Dragonborn Cleric, lvl 15, who has since then been building a Cult dedicating to worshiping Dragons, and bringing them back to a place of prominence. Somewhere along the line, she has found an ancient wizard's spellbook with an interesting spell: True Polymorph.

Her plan is to True Polymorph herself into an Adult Dragon, take the former wirmling as her husband, and with this power and her Cult, rule the world, while starting a dinasty of Dragon Emperors.

The catch is, of course, that there is not a single lvl 17 Wizard that can cast the True Polymorph Spell.

She could have access to one or two lvl 12 Wizards, and probably a near endless supply of 4/6 lvl Wizard/mooks, but not much else in terms of characters.

Now, I'm not asking for RAW, or RAI, (if there is a way, tell me, but don't tell me it's impossible). I'm asking for fluff ideas to DM Fiat a way for the spell to be cast, not necesarily because I want the spell cast, but because it should be a credible threat, and the PC's should be trying to figure out what is going on before it happens and stop it (or alternatively be ready to go toe to toe with a Dragon).

[Nifft]

Things which can't be replicated easily should require a permanent, meaningful expenditure which cannot be replaced.

[Mellack]

RAW the cleric can ask for divine intervention. Assuming that their deity wants dragons to return to the world, they should be able to succeed.

Now if you want for story reasons it to be something that a group of adventurers can interrupt, then I suggest some form of ritual. Many casters working together, probably requiring some important components like the skull of a dragon.

[Ignis6669]

It was never super popular, but 3.5 had rules for "epic" spell casting that might be worth looking at. As written, they're pretty wonky, but they include things like having a ritual, and using minions that give up spell slots and things of that sort. It may be worth a starting point? I would argue that this would be the equivalent of "epic" casting anyway. I'm not super familiar with 5e though, and there may already be a built in answer somewhere that I'm missing.

https://www.d20srd.org/srd/epic/developingEpicSpells.htm

[Reynaert]

I've always been partial to the concept of spreading out such rituals, like with ley lines. So that way the cultists would need to be at several key points all across the land. Maybe the 4-6 lvl mooks are at each of the key points, the 12th level wizards are at some kind of nexus, guiding the energy or somesuch.

[Zetakya]

You need a grandiose ritual featuring all sorts of "draconic" things, like a hoard of gems and precious metals, a volcano lair, a virgin princess sacrificial brunch and so on.

You know, plot hooks.

[Lvl 2 Expert]

Things which can't be replicated easily should require a permanent, meaningful expenditure which cannot be replaced.

This is always a cool option for a villain. It shows how far she's willing to go. Bonus points if it's something they will really only ever have one of. Have her sacrifice the person she loves most, or one of her limbs, or her heart, something like that. (Her spellcasting or the ability to have children are probably not suitable for this specific campaign idea.)

[Sorinth]

For a more RAW way, if instead of finding a spellbook have them find a spell scroll of True Polymorph. Now they can cast the spell but there's a chance of failure, so the BBEG would be doing things to help ensure that the spell doesn't fail, the easiest being hiring a Bard to grant Inspiration, using Guidance & Enhance Ability, etc...

However that would be the advice for a player to maximize the chance of succeeding, it's not particularly hard so the BBEG should easily succeed before the PCs get to do anything. So you are better off story wise just creating some ritual which the PCs have to stop and not trying to do it via RAW.

[Dienekes]

You need a grandiose ritual featuring all sorts of "draconic" things, like a hoard of gems and precious metals, a volcano lair, a virgin princess sacrificial brunch and so on.

You know, plot hooks.

Pretty much this. I’d make the magic complicated, ritualistic, and require active adventuring to get the necessary components.

Also maybe murder is involved. I’ve always been a fan of blood magic for my villains.

[DrKerosene]

It was never super popular, but 3.5 had rules for "epic" spell casting that might be worth looking at.

Since it was available to non-casters, I was a big fan of the rules for Incantations in 3.5e, especially with the failure backlash suggestions (like Delusion and Mirror). https://www.d20srd.org/srd/variant/magic/incantations.htm

I don’t really have anything to add that hasn’t been said. Robbing graves for dragon parts, being in a sacred site to dragonkind, at a specific time of year, with a rare sacrifice, would be my general list. I would like to suggest some weird redherring like requiring a Genie (to be sacrificed instead of using it’s Wish).

[NorthernPhoenix]

As others have said, i'd have it work similar to how epic/high magic (beyond 9th) would work in a regular game. With complicated rituals that require some form of meaningful sacrifice and preparation relevant to the spell in question.

So for True Polymorphing into a dragon, maybe you'd need to draw up a huge magical array with ink made out of a bunch of special materials at a resonant location, then some other steps, then finally sacrifice the dragon in question, or a similar one at the same time as a shapeshifter. Stuff like that.

[BloodSnake'sCha]

You can do it as a ritual that can only be cast when a periocular set of stars aline one in 500-5000 years.

The ritual components can be use as plot hooks.


I just noticed that a lot of people commented that same idea as this.

[Temperjoke]

Alright, a lot of people have already suggested what I thought of first, which is a ritual casting version of the spell.

That being said, you may want to examine the foundation of the situation, which involves an ancient spellbook that had a very high level of spell, used by a wizard of such power they haven't been seen again in a long time. What if the ritual is actually intended to restore the wizard, in exchange for the spell being cast after his/her body has been restored? I mean, on the surface, the party might want to go along with the BBEG, since ultimately the plan is to restore a species that's on the brink of extinction, if there's a more dangerous threat underneath the surface.

[Xapi]

I mean, on the surface, the party might want to go along with the BBEG, since ultimately the plan is to restore a species that's on the brink of extinction,

This is actually a choice I expect them to be faced with. The party will know in advance what will be going on (level of detail depending on how well they do leading up to it) so they will be able to stop the ritual altogether, but also maybe they'll allow it, or maybe they can try to redirect it to a different target, that is not trying to take over the whole continent.

Thanks everyone for the suggestions!