Light can harm you - that's why we get sunburn.
There are spells in RPGs and video games that summon damaging illusions. For example ninja clones are technically illusions but they can damage stuff.
So theorectically I could have a spell in elements that summons and illusion that can impact on the physical world, thus mirage.
When I think of mirage, I think of the type of mirage you see in a desert.
the classical Oasis with plam trees and coconuts surrounding it, I jump for it and start drinking water, only to find that it was a mirage and actually am stuffing my self with sand.
Thats what i think of mirage, an illusion that wasn't real.
I know perfectly well about damagin illusions from other games.
I'm speaking about logic which has nothing to do with other rpg games, and even though elements is a fantasy game, it is still logical in most aspects;
for example:
Steam machine obviously needs heat to produce steam, where do we generally get heat for the steam machine? from fire
.
its fantasy but still logical.