Imagine a sorcerer who scare everyone by his custom to disintegrate every enemy as soon as possible. What to do with him? Cast fooled eyes on him! He will no longer see how damaged his enemies are, instead he will see them as if they have illusion of invulnerability. However this enchant is not effective all the time, sometimes it fails to obscure real damage and victim sees right health state of its enemy and can act according to its knowledge for a while.

See also: illusion of invulnerability