I don't know if you knew this or not, but when blood barrage and ancients first came out, certain spells had certain abilities. A good example of this would be Ice barrage, which can be used at lvl 94 magic, and it's ability is to freeze a player so they are un-able to move. As with blood barrage, it's the same concept, but different ability. The ability for blood barrage was originally for you to gain health, but losing health for casting a spell would have no logic what so ever. This is kind of referenced from Runescape, rather than the server.