As the caster utters the words to this ancient spell, he draws a dagger and prepares to throw. As he finishes the spell, he releases the dagger in an attack against his chosen target (treat range penalties as bonuses to the target's A.C.). But in the short distance from the mage to whatever he is aiming at, the spinning dagger does something amazing. . . it duplicates itself! By the time it reaches its target, a small forest of daggers and knives of all different sizes and shapes assails the unlucky victim.
To be precise, the original dagger duplicates itself a number of times equal to twice the wizards casting level, plus the original dagger (amount of blades = Lv. of caster x 2 +1). Each blade that hits does 1d4 points of damage, 1d3 to large creatures. . . but they can be blocked.
The base amount of daggers blocked or dodged is equal to 1 1/2 the amount that the victim's A.C. is under 10 (Base = 3/2[10-A.C.], round always in the victim's favor). The D.M. might give some bonuses to the victim's A.C. for situation or quick thinking (such as diving flat after the wizard releases the blade, making a called shot to he original dagger to knock it askew before it duplicates, ect.). Any bonuses to the wizard's attack roll for situation (back and flank attacks, for example) are treated as penalties to the victim's A.C. for the purposes of this spell.
Shields are a good difference against this spell; they block extra daggers above and beyond the norm. Even a buckler blocks 2 extra, while a small shield blocks 4, a medium shield 8, and a full body shield 16. Other defenses include hard and soft cover, which block an extra blade per point of A.C. improvement over what they have already done for the victim's A.C. Certain spells would also provide protection against the dagger swarm, notably Protection From Normal Missiles and Ironguard. Any dagger blocked by the spell clatters off of the victim to land nearby on the ground, and remains there for three rounds. After this they silently disappear. The daggers that hit a target remain in existence so long as they are not removed. Once removed, however, they disappear after only three rounds; there is no way to make this spell permanent.
The material component of this spell is the original dagger itself; it must be made of the finest steel, and must be inlayed in precious substances. A gemstone must be set in it's hilt; this stone must be magic conducting (D.M.'s choice of exactly which gems conduct magic well), and be worth at least 100 gp. A rouge stone set in the hilt is especially desirable; if this is the case, the price is effectively 10 times usual for the purposes listed below. The dagger itself must be worth 1000 gp for its make and materials, plus the cost of the gem. This dagger is reusable, however; it is the only dagger that doesn't disappear when removed from the target. It does suffer a bit from the spell, though, as the gem is used to power its magic; each time the dagger is used in the spell, the gem looses 100 gp from it's base value. Once it hits 0, the gem (but not the dagger) will crumble. Thus the gems must be replaced every so often.
A normal dagger can be used as a component for the spell, but only half the amount of blades will be formed, and the dagger will be consumed in the duplication.
When the special dagger is used, the spell gains the power to drag along small blades (daggers, short swords, even arrow heads) and add them to its total, in addition to duplication. The weapons must be within 10' to either side of the daggers path, and must not be being held by anyone. Magical weapons receive a save vs. the effect. These blades are not destroyed, but each, no matter what the blade type, adds but 1d4/1d3 points of damage to the total. The wizard may never gather more extra blades than there are duplicated blades into this spell's dagger cloud.