I remember a story where their magic system uses up mana in the air, so you cannot use too many magic in one area without needing to wait for it to recover slowly.
That sounds like the Warlock trilogy by Larry Niven (Not Long Before the End, What Good is a Glass Dagger and The Magic Goes Away) except in those it wouldn’t recover.
They just know their tropes
https://tvtropes.org/pmwiki/pmwiki.php/Main/ConservationOfNinjutsu
I remember a story where their magic system uses up mana in the air, so you cannot use too many magic in one area without needing to wait for it to recover slowly.
That sounds like the Warlock trilogy by Larry Niven (Not Long Before the End, What Good is a Glass Dagger and The Magic Goes Away) except in those it wouldn’t recover.
Came here to say exactly this :)