You can add to a maximum 10 Skill Points.
Napalm Beat level 3
↓↓+A (+ Air)
Press Down, then Down+Weak Attack
In the air, press Down, then Down+Weak Attack
Summons the spirits with no cast and within the earth to strike its foes. Each soul deals non-elemental damage (600 Power) and travels in a random horizontal arc. The move can be done in mid air. The number of souls increases by 1 every odd level of the skill, giving a total of 5 souls at lv9 and 10. (There doesn't seem to be a reason to level the skill to 10.)
The damage is way lower than any of the basic bolts. The SP cost will hurt your SP consumption at early levels, though at higher levels plus increased SP recovery this is not an issue anymore, although the random height could make you hit thin air or ground, thus wasting a lot of SP. You can somewhat steer the direction of the souls by jumping and executing it in midair; doing it this way it will make it at least hit something.
Don't be fooled by the RBO opening demo! In the final game, Soul Strike has a cooldown of 2.25 seconds, and can't be spammed. This is best learned at high levels when you can afford losing a lot of SP without concern,and the melee battle mage should pick this over the bolts for a projectile attack for a reason later discussed.
SP = 30