Storm has no opposing element, unlike ice and fire. Like with those two elements though, storm element creatures are highly resistant to damage of their type. Few monsters have this element, with the various forms of the Shade along with one of the Guardian's rods being examples of such monsters. All classes have access to storm melee attacks via storm enchantment in their skill tree. Certain classes (Conjurer, Ranger, Warlock, Wizard) can learn storm spells/skills.