Magic is a lost vice, ever rediscovered

(The following is just some loose thoughts: In our game we still use Whitehack's magic rules + d&d spells as unique treasure.)

Magic isn’t really a class. It is a series of bad life decisions.

But sure, let’s say there’s a class. On the understanding that it is a stand-in for a downward spiral, even (especially!) when it seems like an ascent. Those belonging to that class, the magic-users, have payed the price in full, and are versed in the ways of keeping spells in check. Still: There’s a silent minus before the levels: These are basement floors, circles of Hell, a losing of the tethers of reality.

Anyone can start using. The difference is that those who lack the secret regimens and fail-safes of the magic-user must always pay an individual price for every crumb of reality rending they dabble with. Practically speaking: They must pay for spells with a specific curse or disadvantage determined by the referee and connected to the spell’s effect, or (to speed the game along/when feeling uninspired) a generic price of a permanent -[spell level] to their lowest stat (to a minimum of 3, which marks the limits of their ability).

The price of magic must always have a practical in-game effect. Your eternal soul? Sure, but only if it makes people ill at ease around you (-1 on reaction rolls & double wages when hiring) or makes your shadow try to escape sharing your coming doom or whatever.

On Pacts and the Interpellation of Nature

Interpellating the forces of nature has its own problems, related to but distinct from spells: A Pact is a formalized quid pro quo, with the added complication of the tendency of elementals or things from beyond to wilfully misinterpret any command. The skilled jurist may minimize these problems, but never completely do away with them.

Prayers are simply pacts or spells with added sentimentality (generally optional: the observing of ritual is more important than the supplicant's intent).

Innovation is a lost art

"Oh, a way to make people fall asleep? That reminds me of The Dream Thief's Little Helper. Of course, that spell is slightly more subtle than what you are proposing."

A US Commissioner of Patents in the early 20th century is supposed to have said that ’everything that can be invented has been invented’. Apocryphal, it seems, and mostly illustrative of a certain kind of progress mongers’ tendency to reinvent a Dark age that compliments their own forward thinking. (I’m talking about the Elon Musks of the world here, not political progressives.)

But on the Red Planet, innovation is very much a lost art. At least in the spell business. People (and sturgeonites etc) have spent their lives in the shadows of the impossible accomplishments of a dozen Golden ages, and know that this is not one of them. So:

All spells have already been discovered at one point or other in history. Magical research is about finding and, at most, repurposing. Not about innovation. That era is long passed. Since we don't want the npcs to outshine the pcs, they are hacks and philologists as well. Make the spell name the overshadowing presence, never someone with an actual HD.*

So, like Vance’s Dying Earth wizards, Red Planet magic is rote based and almost-always carries the name of a much-more accomplished magician, a splendid city lost to the desert, a god no longer worshipped. Spells are found engraved in tombs, riding packs of jackals or in moldy grimoires. Like this one (reskinned, slightly modded spells from the Old-School Essentials spell lists, with suggested existential prices for non-mages):

Drusticc’s Abridged Dowry

Light of Last Sunrise (Like Light but): Steals a day's worth of light from the sun and stores it in a vessel. Every use shortens the sun’s life with a day; Sets your alignment to chaotic.
non-mages: -1 in lowest attribute OR Insomniac. After use, ST to benefit from your next rest.

The Untimely Passing of the Walls of Oxus (Like Rock to mud but): Turns stone to blood soaked sand, accompanied by the screams of Oxians’ massacred when the last siege was cut short by the sudden crumbling of their city walls.
non-mages: -5 in lowest attribute OR can never lock doors. Not a phobia, but a physical fact.

Ever-flowing Vintage of Tanaïs (Like Create water but): Wine instead of water. Not really created per se, but spirited away from the Imperial wine cellars on Phobos.
non-mages: -4 in lowest attribute OR Roll 1d6 each use: On 6 a cup bearer notices the theft and makes arrangements to trace it back to the caster and/or poisons the wine)

Ruic’s Taciturn Kiss: (Like Silence but): Removes the target’s speech with a kiss. No save allowed.
non-mages: -2 in lowest attribute OR permanently keeps the voice of whoever the caster last kissed.

* Excluding elves, obviously. They are always better than you. Though they did ruin the Green planet with their arrogance, even their failures are played out on a grander scale . The Unsealing of the Cornucopia was a tragedy; the fate of the Red planet merely a drawn-out farce in comparison. (Cf. http://goblinpunch.blogspot.com take on elves)