My world uses a 5-element magic system: electricity (Electro), wind (Anemo), fire (Pyro), water (Hydro), earth (Geo) and tree (Dendro) which will only appear in a spin-off series but I decided to include it anyway.
Each element has a unique property (UP), which is basically a magic effect that is exclusive to the element. I've come up with UP for most of these except for Anemo.
The only element that doesn't have a UP yet is Anemo. I've been researching about the properties of air, oxygen, nitrogen but I still have no idea about what it should be. I always though that air/wind is inert. Probably why most wind magic in a lot of magic systems/media has no sub-magic like in Avatar the Last Airbender (Firebending -> Lightningbending) and when it does, it's usually just flying or a stretch such as electricity/lightning, sound, etc.
Spatial magic is also the most compatible magic form with Anemo although every Element can use all magic forms: spatial magic, healing, construct magic, disruption magic. Magic Form and Unique Property usually have no connection, the fact that it's similar is purely coincidental due to the nature of the elements, i.e. fire burns.
Edit: I decided to readd the UP of the others, I removed it initially since the post was flagged by a bot, lmao.
Electro: Electromagnetism
Allows mages to attract or repel people or things or even magic, electro mages can manipulate the positive and negative charges. Based on the Yin-Yang, males are the positive charge while females are the negative charge.
※Electro was inspired by static electricity and Van de Graaff generators. I came across an explanation that lightning are basically giant static shocks. I liked this explanation and so I decided to make this element around this fact.
Anemo: Decay The Unique Property of Anemo is Decay, because Anemo is the closest to mana, it is capable of inducing corrosion or oxidation on magic, accelerating its decay into mana. In humans, Decay causes mana poisoning: weakness, fatigue, drowsiness, shortness of breath, coughing and wheezing, continued exposure to Anemo can cause organ failure and ultimately, death. In small amounts, Anemo is able to cure illnesses caused by pathogens, although it will initially negatively affect the body.
Mana, in its purest form, is highly toxic (mana poisoning), prolonged exposure to it will lead to death. Magic has a half-life, all magic will eventually decay into mana.
Pyro: Burning
Pyro flames can burn the mana of objects, people and magic and consume it as a fuel source to sustain it. Pyro mages can choose to direct the consumed mana to themselves in order to rpelenish their own mana reserves.
Hydro: Revitalization
Hydro is capable of prolonging the life of living organisms as well as mana/magic by absorbing Hydro, this process consumes the mana of Hydro, reducing it to ordinary water so the mana must be constantly replenished.
※The UP of Hydro is inspired by the Fountain of Youth.
Geo: Fortify
Fortify is the UP of Geo, allowing it to become stronger and more durable up to a certain degree whenever it is damaged by ordinary or magical means. When the damage exceeds this threshold, the Geo will fracture and shatter, releasing a blast of mana.
※Inspired by the work-hardening of metals.
Dendro: Heart
Context: In my world, a being called the "Cultivator" is responsible for creating the World Tree by sowing its own heart, the World is the fruit of this World Tree. So everything was basically created by the desires of the heart of the Cultivator. As such, the heart is the seat of the soul of the person.
Heart allows Dendro mages to tap into the heart/soul/mind of a person, allowing them to manipulate emotions or induce dreams or nightmares.