Are there examples in lore of a dragon learning new spells like a wizard?

Question

I am working on the first main antagonist for my campaign, DnD 5th edition. This will be a green or blue dragon who has the ability to shape change into a human and is a magic user. The dragon will be attempting to gather magical knowledge, spell books, arcane items etc. thereby gathering strength and becoming harder for the party to combat as the campaign progresses. It initially appears as an ally.

I know there is an arcane dragon archetype in the Monster Manual, but these dragons seem to have inherent magic much like a sorcerer as opposed to learnt. I am looking for my dragon to have some inherent magical ability strengthened by utilizing spells more like a wizard, having an ever-growing list of available spells as it gains more knowledge but needing to prepare a set amount each day based on its development.

I am aware that there are differences between Chromatic and Metallic dragons; my antagonist will be Chromatic, so I am focusing on this type of dragon. I am also aware that by allowing my chromatic dragon to shapeshift into a human, I am posisbly going against the rules.

In terms of either Current or historic D&D lore and mechanics, are there examples of dragons learning spells in this way, gathering a magical arsenal in the same way as a wizard would and growing in terms of magical ability over time by learning new knowledge? I am happy if the lore or mechanics ideas come from older editions of D&D that I can tweak to fit in with 5th edition. As per the comments, I realize the pre-WOtC editions where very different and may not be a easily retrofitted to match 5th edition.

I am specifically looking to see if there is any precedent I can work from to try and make this more balanced as the campaign progresses from a fixed list.

Answer 1

D&D 3.5e had at least one.¹ In that edition, sorcerer spellcasting was a common feature on all “true” dragons,² with only a couple of exceptions.³

Relevant to this question, one of those exceptions is the spellhoarding template, part of Dragon⁴ vol. 313’s series on “dragon psychoses.” Templates were a way that DMs could modify creatures in 3.5e, and spellhoarding could be applied to any true dragon to change some of their abilities. Two of those changes were these new features:

Wizard Casting: A spellhoarding dragon prepares and casts spells as a wizard, not as a sorcerer. Use its Intelligence score rather than its Charisma to determine saving throw DCs, bonus spells, and level of spells available for casting. Spellhoarding dragons do not use spellbooks: they memorize spells from their spell hoards.

Spell Hoard: Any spell the dragon learns takes physical form on its body as a rune or arcane symbol scribed upon one of its scales. The dragon may prepare spells from those in its spell hoard just as a wizard prepares spells from her spellbook. To add a spell to its spell hoard, the dragon must complete a process similar to how a wizard scribes spells into a spellbook.

As the name suggests, spellhoarding dragons consider the spells and other lore they know to be their hoard, rather than gold, gems, or magic items. Apparently other dragons considered this behavior “psychotic,” though really considering the absurd power of wizard spellcasting in 3.5e, that position seems quite reasonable to me.

1. _{Bizarrely, Dragon vol. 343’s “tome dragons” still use sorcerer spellcasting, and thus have no need for an actual tome.}

2. _{The definition of “true” dragon is a shockingly contentious one in 3.5e, mostly to do with whether or not dragonwrought kobolds count. But mostly, we’re talking about chromatic dragons, metallic dragons, gem dragons, and so on, and not various “dragon-ish” creatures.}

3. _{Not an exception per se, but it’s worth mentioning that several types of dragon got the opportunity to learn cleric spells with their sorcerer spellcasting. It was still sorcerer spellcasting—being arcane, using Charisma, using the sorcerer spells per day, etc. but they were cleric spells (or spells from certain cleric domains) that a sorcerer couldn’t normally select.}

4. _{Note that at the time, Dragon magazine was published by Paizo, under license from Wizards of the Coast, and not by Wizards of the Coast themselves. It’s unclear how involved Wizards of the Coast was in vetting anything Paizo printed, or how “canonical” it was ever treated. Wizards of the Coast has proven quite willing to ignore even their own canon in different editions anyway, though, so that distinction may be purely academic.}

Answer 2

Yes, 5e dragons can be spellcasters as well as innate casters

In the adventure "Sleeping Dragon's Wake", an NPC green dragon Claugiyliamatar has both innate spellcasting using the innate spellcasting variant and Charisma, and a spellcasting level of an 8th level caster with Druid prepared spells using Wisdom. She has prepared spells = 8+Wisdom modifier

So there is definitely precedent for adding spellcasting levels to dragons as well as the innate spellcasting which uses Charisma.

Just add a spellcasting level to your Dragon, and then give them prepared spells equal to level + stat mod. Remember that any spell DCs will be different than their innate Charisma based spells.

The CR is listed as 23 vs 22 for a standard Ancient Green Dragon.

Also in the adventure a Bronze dragon has 8th level sorcerer spells in addition to their innate spellcasting spells, and has +1 CR.

So if you want to add a Wizard spellcaster level to your dragon, bump up the CR by 1 if you've added enough spells to increase the threat of the dragon.

If you only add a small number of spellcaster levels you don't need to increase the CR, a the DMG says under "monsters with classes":

Depending on the monster and the number of class levels you add to it, its challenge rating might change very little or increase dramatically. For example, a werewolf that gains four barbarian levels is a much greater threat than it was before. In contrast, the hit points, spells, and other class features that an ancient red dragon gains from five levels of wizard don’t increase its challenge rating.

Answer 3

D&D 5e: The groundwork is laid for the DM to do some worldbuilding.

There is nothing in 5e material that says something to the effect of "this dragon learns spells like a wizard". But, you're the DM, you can build your world however you want. That said, there is one particular type of dragon the is the perfect candidate for this kind of design - the Silver Dragon.

In the description of a silver dragon's lair, it says:

Silver dragons dwell among the clouds, making their lairs on secluded cold mountain peaks. Though many are comfortable in natural cavern complexes or abandoned mines, silver dragons covet the lost outposts of humanoid civilization. An abandoned mountaintop citadel or a remote tower raised by a long-dead wizard is the sort of lair that every silver dragon dreams of.

The established lore of silver dragons is that an abandoned wizard's tower is the ideal lair, which is the perfect environment for a dragon to develop its own spellcasting.

D&D 3.5e: Divine spell casting, like a cleric.

The Dragonomicon of D&D 3.5 is a treasure trove of dragon related lore. In this tome, there is a vast array of tools for the dungeon master to use to make dragons more interesting. In particular, it gives rules for giving dragons class levels and prestige classes. Several of these prestige classes are designed as dragons being devoted to a particular god, and so they learn new spells much like a cleric would. One such is prestige class is the Dispassionate Watcher of Chronepsis.

This prestige class allows the dragon to learn new spells as an divine spellcaster would. The feature says:

Spellcasting: From 2nd level on, when a new dispassionate watcher level is gained, the dragon gains new spells per day as if it had also gained a level in a divine spellcasting class it belonged to before it added the prestige class. It does not, however, gain any other benefit a character of that class would have gained (an improved chance of turning or rebuking undead, wild shape, and so on). This essentially means that the dragon adds the level of dispassionate watcher to the level of whatever divine spellcasting class the dragon has, then determines spells per day and caster level accordingly.

The trouble here is that this is utilizing a robust class level system for NPCs, something that D&D 5e does not have.

Answer 4

Certain kinds of dragons in 1e AD&D could prepare spells in a more wizardly way

In first edition AD&D, the different varieties of dragon were listed with percentage chances of being able to speak human languages and, if so, casting spells. From the Monster Manual:

A considerable percentage of dragons have the ability to speak one or more human languages in addition to the language of their species. Similarly, a fair number of dragons which can speak are able to employ magical spells. The chances for either of these abilities occurring in any given individual dragon are shown under the specific treatment by species.

1e didn't yet have the concept of sorcerers as featured in newer D&D, though of the dragons that could cast spells, most were described in a sorcerer-ish fashion. Rather than preparing spells, they simply knew some number of spells, each of which they could use a limited number of times a day (usually once per spell), and more than that those spells known were mostly randomly determined. For instance, the black dragon:

Black dragons which can speak and are capable of using magic can employ one first level spell for each stage of their maturity, i.e. 1-8 spells. Roll randomly to determine which spells they know. The spells known are a special form of the ordinary spells which require only a spoken component, but each can be employed but once per day.

However, silver dragons and gold dragons have a special note in their descriptions that clarifies that they sometimes own spell books and those that do can instead prepare their selections of spells:

Thus, at ancient age a gold dragon knows two of 1st through 6th level spells in addition to being able to polymorph self three times per day. As gold dragons are so intelligent their spells are always of the better sort, and at least half of them actually have regular spell books.

Furthermore, 25% of magic-using silver dragons have books of spells, so they may select spells for use rather than knowing only a limited number per level.

So there is precedent, here, for some dragons to approach magic in a wizardly, as opposed to sorcerous, manner; though this material does date to before such a distinction really existed. And, of course, just because only silver and gold dragons are described this way in the Monster Manual doesn't mean that you cannot rule that other intelligent dragons in your world might also have the same capacity.

Adapting in 5e

5e's rules for dragons as innate spellcasters specifies that the dragon knows a number of spells equal to its charisma modifier, those spells can be of a level no higher than a third of its CR, and it can cast each once a day.

You could simply decide that your particular dragon doesn't have a fixed repertoire of spells, but can memorise a new set of spells by studying spellbooks, so long as the list of spells it chooses complies with the same restrictions. That's obviously helpful for the dragon as it will have a more versatile spell list and it gives it a reason to accumulate magical knowledge, but it doesn't meaningfully change the dragon's challenge rating/combat effectiveness, so should be as balanced as dragons normally are as far as the game's mechanics are concerned.