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I wouldn't just use fire and ice. The classic Four Elements (earth, air, fire, water) have been used for mythological and magical structures for many stories. Look at the Avatar: The Last Airbender...
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Source: https://writers.stackexchange.com/a/28650 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#3: Attribution notice added
Source: https://writers.stackexchange.com/a/28650 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#2: Initial revision
I wouldn't _just_ use fire and ice. The classic Four Elements (earth, air, fire, water) have been used for mythological and magical structures for many stories. Look at the _Avatar: The Last Airbender_ and _Legend of Korra_ cartoon series just for starters. Having mages whose powers fall into one of those four categories (or expand them to metal, electricity, stone, etc. depending on how advanced the civilization is), with opposing pairs, is completely doable. Make it the basis for all your magic, not just the secondary storyline, and if your worldbuilding works, then you're fine. Sure, it's been done before, but there have been lots of vampires and wizards and mages and quests before, and the bookstores are not emptying any time soon. Go for it.