One of my players, who runs a rogue, has long been aware of the paradox that arises when you take a standard-model human thief-type into a dark dungeon. All their skills are optimized to scouting ahead in the dark, hiding when foes approach, and surprising them in the back in a fight.
Except they can't see in the dark.
1st edition AD&D gets around this problem because you'd be a dope to run a human thief anyway. I'm running Basic-type so I don't have that "solution" at hand. But the answer lies in a piece of folklore I'd ben aware of ever since I read John Bellairs' The House With a Clock In Its Walls as a kid:
The Hand of Glory.
Originally, this magical object was not an actual hand, but the mandrake root, supposed to grow under gallows, with soporific and hallucinogenic properties that sometimes led to it being described as "shining like a lamp." Transforming "mandragore" to the French pseudo-etymology "main de gloire," the "Hand of Glory" came to be imagined in English folk magic as the actual hand of a hanged man, combined in some way with a candle made from the fat of that hand - either grasped in the hand, on the back of the hand as in the Gorey illustration, or made by actually lighting the fingers.
Just as unclear is what this Hand of Glory actually does. It is always mentioned as a tool for burglars, but variously it puts the inhabitants of the house to sleep; paralyzes them when they see the light; or opens locks and doors. Also, the flames can only be extinguished by blood or milk.Bizarrely, the version found in the 3rd edition D&D SRD allows the holder to wear an extra magic ring. (You have to wonder about the kind of campaign this would be useful in, where characters are going around tricked out with three or more magic rings.) Charles Stross' Laundry novels of modern magic take the Hand even further by treating it as a sorcerous zap gun.
But the one legend of the Hand of Glory that solves the thief's dungeon problem is the lore, also used in the Harry Potter novels, that it emits a light that only its holder can see. This is the basis of my Hand of Glory.
Hand of Glory
Availability: -6 (can be reliably had in only the largest metropolis)
This magical item is made from the hand of a hanged murderer. It is considered a disreputable item of sorcery, if not evil in itself. When properly mummified and prepared, the hand grasps a candle made from its own fat. The lit candle burns for an hour and illuminates a 20' radius with a sickly yellow light that only a person holding the Hand in his or her own hand can see - the light source is invisible to normal and darkvision alike. Thus, it is prized by experts in sneaking and hiding, for it lets them explore completely dark areas without being spotted.
The candle also may not be extinguished by any normal substance other than a life-giving bodily fluid - blood or milk. If so extinguished, however, it may be lit and used again for the remainder of its burning time.
Making a Hand of Glory requires 150$ in materials, one full day's effort to prepare, a month waiting time, and the casting of continual light, invisibility, infravision, and continual darkness on the same day at the end of that time. The most difficult requirement, of course, is that of the hand itself; many enlightened rulers now order the cremation of hanged criminals to prevent their use for black magic of this kind.