Arcanoreactivity is a phenomena whereby certain beings exhibit a response to magic within the area they are in. Arcanoreactive beings are often mistakenly referred to as 'having auras' -- in fact, all beings have auras, some are simply more sensitive than others.
Reactivity comes in multiple types.
Attuned beings are developed to fit within a very specific manascape, and are incapable of surviving outside this environment or a very similar one. Attuned beings often have powerful nature-based magic, but only within their domain. Nymphs and dragons are examples of attuned creatures.
Adaptive beings show a strong preference for their native manascape, but are capable of living outside it. If moved to a different area, their children will show marked changes and be attuned to their new environment within one generation. Ammen'ari are an example of this kind of creature.
Inert beings make up the bulk of all life on Sharra, and display no special response to magic, which makes them far more tolerant of phenomena like the Wastes.
Hyperreactive beings exhibit real-time responses to changes in the magic of the level on a minute level, including mortal spells as they are cast.Wisps, starflowers, and witchrats are examples of this kind of magic.