Fully described in FR4/The Magister, the powers of this useful item are summarized here.
A glowing globe is a luminous glass globe that always floats above and just behind the shoulder of the person who first touched it. Its brightness is controlled by silent use of the owner's will, varying from completely dark to blinding (a brief flash; creatures within 40' of the flashing globe save vs. spell to avoid being blinded for 1-6 rounds). Such a globe can be removed from an owner's control by remove curse or a limited wish, whereupon the next being to touch the globe inherits control of it.
A glowing globe does not give off any heat. It is AC4, and can be shattered (causing a blinding flash, as above) by doing it 14 points or more of impact damage; magical or normal fire, cold, and lightning will not harm it. It cannot be made invisible except by use of a wish.
A glowing globe is affected by changes in its owner's state, and drops to the ground, lightless, if its owner is killed, petrified, goes ethereal or astral, or travels to another plane without taking the globe along. Control can be gained by any being touching such a lifeless globe.
If a sling or harness is thrown over it, a glowing globe's levitation can allow it to carry up to 20 pounds. Any weight above 21/2 pounds causes a globe to slow to the pace of a slow walk-MV 6. Some mages reduce their size and move along with a globe, though this mode of travel is hardly common.
Driftlights: One specialized form of glowing globe widely-encountered in Undermountain is known as a driftlight. It is larger and brighter than a standard glowing globe. They are rarely under the control of anyone, except by purely physical means (i.e. the use of nets to drag them along). Driftlights are set free to roam, once created, providing illumination equal in effects to a continual light spell. They levitate about, lasting until physically destroyed or until their magic is dispelled. A dispel magic spell merely blacks out the light and levitation of a glowing globe or driftlight for 2-5 rounds-an antimagic shell, limited wish, or other, more powerful spell is required to destroy either form of globe forever.
Text from The Ruins of Undermountain: Campaign Guide to Undermountain by Ed Greenwood ©1991 TSR Inc. Fnord