Omnipower is an ultimate ability associated with the Magic skill. It requires level 60 Magic. When activated, the user conjures a powerful spell that is enhanced with all four elements (air, earth, water, and fire) that, if it hits the target, deals damage equal to 25% of their maximum life points. Omnipower respects the damage cap that is in place on certain boss monsters; for example, it will deal 5,000 damage to General Graardor instead of 13,750 (25% of his maximum life).
Although Omnipower's description and animation make it clear that all four elements are used, it will not be any more accurate against a target that is weak to a specific element.