Elemental skill

After you purchase the Spellcasting Special Power, you can buy ranks in any of the magic spell schools you are able to learn. See the Magic chapter for a list of schools and the spells available. You can add your Spell rank to to both Casting Rolls and rolls to defend against the spell. Your number of ranks in the school affects not only the rolls you make to cast the spell, but potentially also the length of time it lasts, or how big an area it can cover.

See the Magic chapter for more details on casting and resisting spells.