If you have telepathy, you should hear the quest leader’s telepathic summons message more clearly than its current garbled state (perhaps “m..ic transporter”), and if you have extrinsic telepathy, you should hear it with perfect clarity.

Telepathy currently sees things with minds. Change it (or perhaps change only the amulet of ESP, leaving other telepathy the same) so that it sees things with souls instead of minds. Mostly this corresponds with the same monsters (with a few exceptions such as mummies which are animated by the soul of the dead person), but if a monster with a soul is polymorphed into a form that normally doesn’t, it retains its original soul, and shows up as its original form to ESP.

Additionally, ESP shows the spirit of a humanoid with a soul just after you kill it if you’re blind, making some angry or resigned gestures before fading away.

Intrinsic telepathy only works in a radius equal to your Int (extrinsic sources aren’t changed). Cooperative telepathy, if implemented, works in the same radius if intrinsic, full-level if extrinsic.

If you can see a monster only with telepathy, you cannot see its peaceful/hostile status, so all monsters appear hostile by default (except tame monsters, which you can still see as tame). Likewise, you can’t see the monster names of non-tame monsters you can see only with telepathy.

Ranged divination effects (monster detection, object detection, clairvoyance, maybe telepathy) are suppressed if the level is not mappable.

Some monsters can block being detected by your telepathy, either innately (disenchanters, perhaps) or as a monster intrinsic conferred by armor (such as a tinfoil hat) or spellcasting by an ally. Also, possibly allow for area-of-effect “telepathy dead zones”.

In certain cases, you can see what telepathic monsters can see in a radius of 2 or 3 centered on the monster, assuming it fails a saving throw versus you reading its mind.

Rings carried by Nazgul are all artifact rings of invisibility. They autocurse and also confer telepathy, see invisible and aggravate monster.

If you are a Caveman, you get telepathy or clairvoyance while you are hallucinating.

Artifact chaotic amulet Amulet of Splendor: provides every single amulet effect, as well as unchanging-ignoring controlled polyself when invoked. Wearing it conveys life saving (this WILL disintegrate the amulet if triggered), magical breathing, unchanging, poison resistance, ESP, reflection, strangulation (doesn’t kill you due to magical breathing but maybe it makes it so you can’t eat food or something while wearing it, or it autocurses), restful sleep, and gender change for as long as you wear the amulet. Base type is a cheap plastic imitation of the Amulet of Yendor.