Influence 

Rainbow (band) may have something, that was taken from them to Power Metal, (I think mostly, it split into DIO and Blackmore's Night, with booth have epic themes), but they are definetly not Power Metal themself... BTW Deep Purple count as inventors of Speed Metal, which is the style, from which Power progressed... So, my opinion is, that Power got direct influence from Rainbow, Deep Purple, as was said and is stated in the article - Judas Priest and Iron Maiden... DIO is primary more an influence, or a-very-predecceccor of this style... I think someone should add the "influence list" and transfer before-Helloween bands there... I could try, but now am too busy.