Negate Magic

Even the strongest spellcaster trembles before this spell. All the pride, all the hubris is gone as soon as this incarnation is spoken, as it stops the working of all magic in the area for a limited amount of time. Magical creatures like Liches and Gazers are practically crippled, while enemy spellcasters can only do the wise thing, and run.

Sometimes, the spell is simply called "Negate".

Trivia

 * The Crown of Lord British does the same thing, with no time limit. Without it, surviving dungeon Doom is impossible.
 * The Storm Cloak also negates magic.
 * There are certain areas in Ultima VII, where a negate-effect is active.