The primary casting cost source comes from dice with a different element in each face. You earn more dice over the course of the game and casting costs are met in a press your luck fashion. Lore-wise, the idea is, as a magic user, you find these elements around you and channel them into your spells.
At this point the four basic elements are fire, earth, air and water. The basic dice are either 4 sided or 6 sided (with a colorless side and a wild side). 8 sided dice are upgraded from basic dice and contain a randomized assortment of non-basic (acid, lightning, etc.) and basic elements.
But now I'm second guessing my choice of elements. Just seems too vanilla and cliche. Sticking to the current mechanics, what are some other elemental type systems I could use? Thanks! :)
I've actually been tossing around the idea that higher order elements are compositions of lower ones. So rolling a water and a fire could combine to make steam or, conversely, a steam on a larger die could provide water, fire or both.
There are also ways to gain/store/manipulate elemental charges, so you would not be entirely at the mercy of your dice rolls.