Random_writer
Idead #1: elemental healing - as Doevm/Cerlius said before, people on that world think that only light/holy magic can heal people. But there are other ways to heal, like controlling the blood to coagulate and stop bleedings (Though I'm not sure if controlling blood is in water or dark domain). Idea #2: elemental rose - a rock stem riddled with air blades as torns, water/ice petals and a fiery core in the center. Idea #3: steel breaker - series of intercalled waves of heat and cold with the sole purpose of causing thermal shock.
submission 1, something that fundamentally changes magic could be using "inverted" fire magic ie it makes the area cold but restores mana. the replenishment could be slow to the point of it being impractical or effectively useless in a fight but it would be very doevm to turn the entire understanding of magic on its head (atleast what i understand of the system). circles could be something like "fire/heat" "absorb" and then a component from holy magic or dark magic where it speeds up the natural accumulation of or "creates" mana.
How about using ripples on a water surface and then hardening them to keep their position to break the light that hits the water surface in such a way that something lying at the bottom of the water body is hidden? Or using air magic with dense/slow/hard characteristic to either slow enemies down or even bind them with invisible shackles?