This spell had a duration of 4 minutes, and during that time the caster could stop or reflect a single mundane or enchanted physical missile, such as a rock, a crossbow bolt, a javelin, a throwing axe, an arrow +1, a vial of holy water, or a flask of oil. A single magic missile could also be targeted, but was simply canceled with no chance at reflection. If the missile was reflected back to its source, missile mastery granted a significant improvement to the original sender's chance to hit. Concentration on this spell was not required, so the caster could move and fight, but targeting a missile or casting another spell terminated missile mastery.
There were range and size limitations on the missile, and enchanted missiles had a chance to resist being affected. To be a viable target for this spell, the missile had to pass through a sphere centered on the caster of radius 10 yd (9.1 m) per experience level of the caster. The source of the missile did not have to be within this area, only the missile in flight. The weight of the projectile could not be greater than 1 lb (2.2 kg) per level of the caster.
Only verbal and somatic components were required to cast this spell.
- ↑ There is a discrepancy about the number of missiles that can be affected. The spell description uses the phrases "one missile", "single missile", and "only one particular missile... in a single round", but then also says "a single missile per round" as if more than one were possible in other combat rounds. Since the Area of Effect is given as "one missile", this article uses that figure.