I've been a fan of the movie "The Covenant", not for it's plot, but for the way magic is used. In the movie, the sons of ipswich are able to use magic, but it is very addictive and it ages you rapidly as you use more and more. I like this idea because in many of the books, movies, and comics(not all of them) this is one of the best way that using magic is shown. I've tried to use this as the way to describe magic, but I worry about copyright laws.
Don't worry about it. I'm sure the Covenant wasn't the first piece of media to use the idea. The concept is a concept. And concepts in and of themselves can't be copyrighted. If you were to take the basic pretense of the magic being harmful to the body in a manner akin to hard drug use and apply it to a completely different story line and characters of your own there's no problem. Heck. In the world of writing, you could probably just changes the names and settings and still not violate copyright XD. If Chris Paloni can rip his story line out of Star Wars, you can barrow magic from the Covenant (Just be more inventive than Paloni was...).
I thought Paolini included lotr in his pathetically written book? Sorry, I won't hijack this thread ... Concepts are free to roam, killer plants aren't copyrighted, little green men in flying saucers, though more specific, still not copyrighted ... I think it's more characters, plot and worlds which are copyrighted than concepts. Just have fun, so long as you're writing is better than a certain aforementioned author...
I recall that in the movie "Stardust," every time the witch characters used magic, it aged them noticeably. So the idea isn't exactly a unique one.
Not a unique idea at all. There has to be some sort of drawback to the use of the magic otherwise the characters who have magic can do whatever they please and, as far as a plot line is concerned, they end up holding a trump card that makes all other actions by all other characters kind of ridiculous. Like playing rock paper scissors with the one kid who always wants to introduce dynamite as a valid choice which beats all of the other choices. Why bother playing? Just please don't use the word seductive in every fifth sentence like they did in the movie. That got under my skin.
Only completed works or works that have a transferable format (paper, computer file, etc) are copyrighted, and once the works been copyrighted, it's specific universe, characters, imagery, and theme are the sole property of the creator. But copyright doesn't say you can't make something similar or along the same lines.