I agree that there are probably more than the basic 5. I've heard of lightning, metal, ice, shadow, light, all considered elements. I guess it depends what you believe as to how you incorporate it in to use. We all know a spell or ritual is only as powerful as the belief, faith, and intentions behind it. Perhaps elements work the same. I will say that I do NOT believe blood to be an element and blood, to me, should only be used in rituals and spells as symbolic or connective with higher powers, to use it otherwise would be an offering like a sacrifice and that leads to darker things.