Anti-magic zones

Variants:
* Simply prevents magic from being performed or functioning within the area, spells fail without producing effects, magical beings die or simply feel deaf/blind when entering them, etc.
* Magical energy is rapidly expunged from the area and anyone entering it, causing any attempt to cast magic spells fail due to lack of magical energy. Some may still manage to cast spells in such areas if it doesn't eliminate energy regeneration (and therefore potentially person being able to generate energy faster than it is drained).
* Anything magical is prevented entry or is destroyed upon entry. Similar to the two above except the effect can be devastating to anything magical or magically oriented.
* Permanently performs any of the above. Becoming rather devastating to magic items, wizards, magical beings, etc.

Implied: (not enforceable)
* Magic (in case it negates some non-magic like powers, e.g. a radio dampening field that disables powers based on control of an invisible swarm of nanobots)

See also: power negation