Telepathy is a passive ability that allows players and monsters to detect non-mindless creatures, regardless of whether or not they can be seen visually. Telepathy comes in two types: the less powerful intrinsic telepathy and the more powerful extrinsic telepathy.
Intrinsic telepathy only works when you are blind, and detects all non-mindless creatures on the level. Extrinsic telepathy does the same thing as intrinsic telepathy, but additionally works to a lesser degree while unblind, to a maximum range of 8 squares. (Because intrinsic telepathy is typically acquired before extrinsic telepathy, some players mistakenly think extrinsic telepathy does not show the whole level while blind.)
Intrinsic telepathy can (sometimes) be acquired by eating the corpse of telepathic monsters, eating an amulet of ESP, or polymorphing into a monster with telepathy. Note that eating a (master) mind flayer will not grant you intrinsic telepathy if it grants you a boost to your intelligence. While floating eyes will grant intrinsic telepathy with 100% probability. Intrinsic telepathy can also be gained after #praying to your god under certain circumstances.
- The Longbow of Diana
- The Orb of Detection
- The Magic Mirror of Merlin
- The Platinum Yendorian Express Card
Note that it is possible to have both intrinsic and extrinsic telepathy at the same time. In this case, the more powerful extrinsic telepathy is used.
Extrinsic telepathy can, as is usually the case with extrinsic properties, be lost by removing from main inventory or unequipping (depending on type) the item granting telepathy.
Mindless monsters (occasionally referred to as "brainless") cannot be detected by telepathy. See the "Mindless" article for a list of mindless monsters.
Downsides to telepathy
Mind flayers and master mind flayers can detect the location of telepathic players, and attack them with a long-distance attack dealing d15 damage ("A wave of psychic energy pours over you! It locks onto your telepathy!").