Opposite Reaction (Psionic)

Acting upon a single missile attack, this power blasts energy of equal power from the missile in the opposite direction, presumably striking the attacker. The missile must be physical, not magical. The psionicist must see the missile and use the power as it is being fired. For bow and crossbow weapons, an arrow of force automatically strikes the archer, causing damage as if it were the missile itself. For spears, chatkcha, and other thrown weapons, the missile of force must make a successful attack roll, using the thrower's THAC0, to hit. If it misses, it may strike others standing behind the original thrower, such as ranks in military formation. This power has no effect on the physical missile fired the missile functions normally. If the physical missile is flaming or magically enhanced, the blast of energy does not gain those attributes.
Power Score — The blast of energy is so great that, in addition to its normal effects, it may break the firing weapon the bow or crossbow, or the arm of the thrower. Items may save vs. crushing damage. Creatures get a Constitution check to avoid damage.
20 — The force is instead added to the original physical missile if it hits, it inflicts double damage.