Jack Vance

Jack Vance is an Appendix N author, which is to say required reading for the Dungeons & Dragons system. Most famed for the Dying Earth series which he'd inherited from Clark Ashton Smith's Zothique.

Among /tg/, Vance pioneered the notion that magic is a tool usable by any adventuring party, rather than (as Smith) a ritual likely to ruin one's soul therefore fit only for NPCs. That meant magic needed at least to pay a respectful nod to the Thermodynamics. (His books also demand that his mages, like GMs today, learn mathematics.) Hence: Vancian Casting, where the mage must learn a fixed number of spells per day and then fire them off.