Darts of force

Essentially this is a version of the magic missile spell commonly known to all mages. As with most variants up to five missiles of pure magical energy can be projected at a target or targets, in most cases rendering them insensible or outright killing them from a combination of physical kinetic impact and system shock.

Use and Practitioners
The best known user of this variant of the magic missile spell is Pharaun Mizzrym. Favoring the ability to eschew with material components and still cast a (relatively) potent spell, it has saved his life on more than one occasion. For this same reason the spell is generally coveted by any mages who know of it's existence. It's most common users are Underdark Sorcerers, Underdark Wizards, or Multiclass characters who wish to retain spell casting capability without their material components.

Where to find it
The most common place to find it is in a spellbook of an underdark magician. Surface mages DO indeed posess the knowledge of the specifics of this spell, however it has not widely disseminated it's self into the general pool of common spells that most surface wizards draw from or learn in their academy days. Strangely, considering the underdark's citizens' general distrust of one another and constant scheming and one-uppery, the spell is much more common in underground campaigns and settings. This seems counter-intuitive until you realize that the harsh underworld holds many dangers, and one (especially an unarmored mage) must have some sort of defense ready at all times, especially when at their most vulnerable. The lack of material components makes this spell a fantastic weapon of treachery or last resort, and since necessity is the mother of invention it is no wonder the underdark wizard community, and the drow in particular, were able to tease out it's secrets and spread them far and wide. There was just more need of such an animal, and by that regard more wealth to be had by it's spread.