In case if anyone interested, I've recently found a pretty obvious thing I have missed before:
to design those custom abilities, I need to design complete magical system/rules first. Not "how to make those abilities" (current thread), rather "how exactly any ability will affect the world".
For now I'm looking and comparing existing RPG magic systems (mostly from tabletop games), but anyway will need to design own system for my abilities. To make it simpler, let's assume that abilities can only affect characters (players, NPCs, mobs) and can't affect world/environment (terrain, buildings, etc).
One possible way is to make each object to have a property for each particles type. E.g., Temperature for Fire, Wetness for Water, and so on.
So, particles will affect own property and it will results in some visible effect.
The hard part is – while things like "temperature", "wetness" or "health" (for Life/Blood particles) are obvious, I'm not clear what to do with Earth (strongness?) or Air (?), not talking about other types...
Trying to think any other ways how to design it on low level, but didn't yet found anything.