Inventing New Spells

==3e magic==
Pg 85 has the Improvised Spells section which states "Only a mage may improvise spells" (ie not non-mages who can cast spells they've learned in High Mana areas) with pg 87 mentioning:
:"A spell is created by taking a magical verb and a magical noun, and willing them to have a specific result. This allows for unlimited invention of new spells."
Unlike 4e where you could improvise spells in a college you did not know any spells in (albeit at a -5 penalty) 3e required you to know at least one spell in that college, meaning you could not improvise spells if you knew no spells to begin with.
3e used a system similar to 4e's "ritual magic" where you had "skill in a college" with an effective character point investment based on your relative skill in various spells within the college.
Since this was based on modified skill as opposed to the character points invested in those spells, it rewarded higher-IQ higher-magery players more than those who specialized in spells.
==fantasy==
F167 has Theoretical Magic and Spell Design rules related to this
it usefully elaborates on how to extrpolate a major bug v a minor bug into magic terms (crit fails and nuisance effects)
==4e magic==
M14 rules for applying the New Inventions rules to creating new skills.
==sorcery==
in GURPS Sorcery. includes:
#Multiple-Advantage Spells
#Perks as Spells
#Disadvantages, Skills, and Techniques
category:rule sets