Patent law protects novel, non-obvious, and useful inventions, and a magical spell arguably satisfies all three criteria, provided the wizard filing the claim can demonstrate the incantation was not previously known or practiced.
The novelty requirement is the first major hurdle. Given that spellcasting traditions often stretch back centuries, establishing that a specific incantation has never been publicly disclosed requires an exhaustive prior art search through grimoires, oral traditions, and any previously filed magical patents.
Non-obviousness presents a subtler challenge. A spell that simply combines two well-known incantations in a predictable way may fail this test, whereas a genuinely novel combination producing an unexpected magical effect has a stronger claim to patentability.
Utility is rarely disputed in these cases, since most spells are developed for a specific practical purpose, whether that is transmutation, illumination, or aggressive weather manipulation against a rival kingdom.
Infringement analysis compares the accused spell's incantation structure, gestural components, and required reagents against the patented claim. A wizard who alters a single word of the incantation while achieving an identical effect is unlikely to escape liability under the doctrine of equivalents.
Damages calculations pose unique valuation questions, since magical spells rarely have a comparable market price. Courts would likely look to licensing precedent from similar spells or expert testimony from established magical guilds regarding fair value.
The practical recommendation for wizards is to document spell development thoroughly, including draft incantations, testing logs, and dated correspondence with any collaborating enchanters, well before disputes arise.