ESP is an abbreviation for Extra-Sensory Perception. ESP means perception which occurs independently of sight, hearing, or other senses, and is sometimes referred to as the "sixth sense." An amulet of ESP grants extrinsic telepathy when worn, which will show all monsters with brains within a 10x10 grid.
This amulet can be identified easily with the far look command. If you notice a monster on screen that you wouldn't ordinarily be able to see (e.g. on the other side of a wall), far look will tell you whether you are seeing it because of telepathy. If so, and you have no other source of telepathy, it must be coming from the amulet.
Amulets comprise 1% of all randomly-generated items in the main dungeon, 1% in containers, and 4% in Gehennom. With a chance of an amulet of ESP being generated at 17.5%, this is the most commonly generated amulet, and one of the best: telepathy while non-blind provides excellent early warning of approaching monsters.
- The Eye of the Aethiopica, an artifact amulet of ESP