It gives your attacks elemental properties. With each new level of the spell up to level 7 it adds a new element. The elements are applied in the following order: Ice, Body, Poison, Death, Lightning, Mind, Fire. It's not all that useful of a spell unfortunately because the enemies you'll really want to use it on usually don't have elemental weaknesses, and many actually absorb elements as well. Haste and Berserk are both much more useful, and if you only take one I reccomend Haste.