Spells etch themselves on the inside of the wizard’s skull in the language of sorcery. To get a new spell you need to crack that skull open and tame the spell so it will etch itself on your skull’s interior. A little Vance and a little Reichert inspired this thought.

Vance’s Dying Earth series needs no introduction here – one of the seminal works of fantasy fiction and a huge Appendix N inspiration to our favorite game about dungeoning dragons, it is the basis of the Magic-User/Wizard class and its spell memorization. Magic, being a wild, living thing, takes a tremendous amount of work to pin down and to cast a spell is basically to release it from the cage you trapped it in when you memorized it that morning.

Reichert’s Nightfall duology is a lesser-known fantasy series about a titular legendary thief and assassin who is captured and oath-bonded to assist a young prince. Nightfall himself is a sorcerer, and in this universe sorcerers are basically X-Men mutants trapped in the rules from the movie Highlander. Some are born with a manifestation of magic: one unique power. Nightfall can become as light as a feather or as heavy as a stone merely by thinking of it, making him an expert prowler and burglar. Some sorcerers are not content with this, and they slay other magicians to steal their power in a form of ritual murder.

In D&D, often you will gain the opportunity to learn a spell by slaying a combatant wizard and grabbing up his spellbook in your greasy little hands like the ghoulish crook you are. But, why stop there? Why not take this a step further?

What if the wizard had a spell trapped in his mind, literally etched on the internal surface of his skull as you would record it on the pages of a book with a quill. What if he had many? What if monsters did? Since magic is a living, vital force – and capital-M Magic is a language (Read Magic is, after all, universal to all written magic; it’s not Read Elvish Magic or Read Abyssal Magic), why couldn’t it etch itself into the skull of that dragon you’re fighting?

And now we’re here.

I mean it’d be a cool idea and all just as a form of flavor but we can go farther. We can add some mechanics or something to play with. It doesn’t need to replace extant systems for finding magic spells in the world – texts still exist, scrolls still exist, and so forth – but it can create a potential for a higher-magic world with a high-risk, high-reward gameplay reinforcement. A mage’s spellbook may have some of her spells, but so too will her skull, and it may not necessarily be the same assortment of spells in both sources. Similarly, some enemies who use magic who may not have grimoires will have the spell etched into their skulls, creating opportunities for player characters gaining spells if they will take their chances fighting the beasts.

So:

1. All creatures which use magic – real, actual spells, not just inherent magical abilities – have the spell etched on the inside of their skulls. This means Magic-Users, this means Clerics, this means Liches and Beholders. Mortal magic-users and their ilk will only have the spells they have prepared etched inside their skulls; cast spells disappear as if they were never there.
2. Many spells, many etchings. The etchings are always in the language of Magic. More powerful – and therefore, more dangerous – spellcasters will have more stuff in their head and therefore more chances to successfully retrieve a spell.
3. Many spells exist in only one skull. It behooves you, as a practitioner of magic, to get at the inside of those skulls.
4. Cracking the skull like and egg is necessary to see the etchings. You have a one-in-six chance to successfully open that skull and get at that spell without shattering a critical portion of the etching or letting all the magic escape.
5. Creating conditions for success – preparing a fancy ritual, using fine skull-cracking tools, preventing damage to the head during the preceding combat – can give better odds. Maybe seeking out a learned hag to discover the ritual of skull-splitting gets you to two-in-six odds, and using tools stolen from an ancient cannibal cult’s priest gets you to three-in-six odds.
6. Once you get at the spell etched inside the skull, and you overcome the odds to reveal it in an undamaged and intelligible state with remnant magic still present, roll chance to learn new spells as normal.

This incentivizes mages (and parties with Magic-Users) to seek out and combat magical foes and casters rather than avoid them, so there may be knock-on effects here. It also encourages parties to fight to the finish against certain enemies when they may otherwise cut-and-run. It also provides clear reason for mercenaries, rival parties, enemy warbands, and big bad necromancers to want to murder the party and slurp out their delicious skull words.

Hopefully, this works for you or at least gives you an idea for an image or a system to employ in your games! As always, you can get in touch with me here in the comments, or you can go peel open my skull on Twitter where I post multiple times per day as @DungeonsPossums.