X-Ray

With walls or mountains blocking the line of view, X-Ray enables the caster to simply look through them, as if they are made of glass, for a short time. Very useful for finding secret doors and passages. The white potions originally had the same effect.

Both the spell and potion were outlawed after an infamous peeping-tom scandal at 207 A.E.

Trivia

 * The true reason why this spell vanished by Ultima VII is that the game engine acted as permanently using X-Ray, making the spell and potion useless.