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.

Mechanics
This spell requires only a movement of the hands and vocalizations of a few syllables. Depending on the power of the mage between one and five tiny balls of magical force resembling small orbs of colored magical fire will streak to their target without fail. This spell never misses it's target. In game terms one missile is gained at every second level after first (1st, 3d, 5th, etc) with each dart doing 1d6 damage. A mage may not launch more than 5 missiles at a time except in case of extraordinary circumstances. Such could take the form of new metamagic, or creative use of other magical effects and supplements.

Appearance
This spells exact proportions and appearance, like it's parent spell magic missile, vary considerably from caster to caster. Depending on the whim, outlook, power, alignment, disposition, and even mood of the caster the spell can take an almost infinite amount of forms. Variables include color, size, speed, pattern of movement, and even overall visual presentation. Although the change is only a cosmetic one, the power of the spell remaining constant, the variability of this spell can prove a boon to a clever adventurer. For example, Aedith's darts of force could take the form of the universally recognized tiny balls of blue flame synonymous with the standard magic missile spell, while the next day when she's in a cross mood they could appear red. Denton's darts of force could take the form of solid shiny metal balls, or demon's heads with opened maws streaking towards their target. Although mostly this is an unconscious manifestation, some mages are able to shape their darts quite puissantly, having them appear as whatever is most beneficial at the time. Because of their innate ability to shape magic into recognizable forms, illusionists and gnomes excel at this sort of magic.

Where to find it
The most common place to find it is in a spellbook of an underdark magician. Surface mages DO indeed posses 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.