Gives the wearer ESP, allowing one to sense monsters and shopkeepers via a sphere above the creature which can be seen through walls.
Based on the features of the sphere the wearer can tell if the creature is hostile, friendly, or sleeping. The sphere also indicates roughly how powerful a creature is, how much health remains, and any intrinsic abilities(e.g., poison resistance, cold resistance) the creature may have.
Green indicates the creature is friendly. Red indicates that a creature is hostile White indicates that a monster is asleep.(If an ally is sleeping, it will remain green) Yellow indicates a mold or lichen. Blue indicates a shopkeeper.
An image of a poison gas cloud shows that the creature can resist the effects of poison. Glow means a plant.(incomplete list)
If there is more, edit them by immune to physical attacks, etc.