Increases the damage of your Arcane Missiles spell by an amount equal to X% of your spell power and the damage of your Arcane Blast by Y% of your spell power. In addition, increases the damage of all party and raid members within 100 yds by Z%.
Arcane Missiles normally gets 142% of Arcane spell damage applied to the total damage of the spell, distributed to each tick evenly over the 5 second channeling time. The talent bonus is added to the base bonus, where at max rank the bonus is increased to 187%. The following formula gives the spell damage coefficient, where X is the number of points in the talent: