Mmmagic. Maybe this will provide some ideas. Also, feel free to share your own elemental systems if you like. I know I'd appreciate it
First, a brief intro to the Vaitassien.
Only present in humans and elves. Magic flows and pools into these mental wells. Not everyone has one but they are common. Most only have a shallow Vaitassien. The deeper it is the more powerful the carrier's abilities are and the more likely they are to have a powerful affinity. Those with shallow pools don't have affinities and if they happen to it's usually only one and a simple form of magic.
Onto elemental magic.
The most common form of magic is elemental magic. If an individual has an affinity the chances of it being elemental is very high and if someone has several affinities at least one is usually elemental. Sometimes and usually uncommonly, those with an elemental affinity develop a physical mutation that corresponds with the element.
List of elements and mutations-
Ice (Mutation: body temperature runs unusually low and they are vulnerable to the cold but can withstand high temperatures)
Water (Mutation: have strong lungs and can hold their breath for unnatural lengths usually coupled with increased stamina)
Earth (Mutation: stronger than usual without training and have slightly tougher skin which means resistance to physical injuries)
Air/wind (Mutation: lighter than their body type suggests and they can fall from greater heights without injury)
Electricity (Mutation: able to move faster than usual and they have increased accuracy in general)
Plants (Mutation: don't need as much sustenance or the usual nutrients from food)
Fire (Mutation: body temperature runs unusually high and they can't handle the heat but do well in uninhabitable cold climates)
Mutations only affect a carrier slightly and are sometimes not noticeable but there are rare examples where a person is more dramatically affected. Elemental magic is also incredibly flexible and the uses of it can be nearly endless if the user is skilled and practised enough. This magic usually requires the least training for basic usage but mastering them can take years. They also cause the least negative effects.