Dungeons and Dragons: Mithrondil's Spell Book, Page 4

As promised, this spell has to do with psionics. Mithrondil met a new companion (a new player entered the game) and she had some amazing abilities. Strangely though, she never seemed to need spell components and she seldom even had to exhibit any outward show that she was doing anything at all. He finally equated this to the abilities of the Mind Flayer and set about devising a way to determine whether these powers were in use. His first thoughts were that, since he had someone nearby to test it on, he might as well try. It would be useful in the underground to determine whether or not there were any Mind Flayers, or similar creatures, in the immediate area. He later had reason to believe that he should be on guard against this new party member as well, but that's another story.

The spell is called, "Detect Mental Powers", for obvious reasons. It is part of the Divination school of magic and, therefore, akin to Detect Magic, Detect Evil, ESP and other such spells. Mithrondil set it at level two spell use, being a bit more powerful than the first level spell, Detect Magic, but not as powerful as Detect Scrying, a fourth level spell.

The spell has a range appropriate to its level and a duration that increases with the caster's experience level. The area of effect is a straight line path, but the source does not have to be visible to be detected. Thus, mental powers may be detected if the source is hidden or invisible and the direction will be noted, but not necessarily the distance to that source. The DM is free to say that some materials interfere with the determination of distance more than others.