An idea for a more Mathematical Vel'koz
A new passive mechanic somewhat similar to Fiora's, except that his is triggered by hitting it from a certain direction with his abilities. The big difference is that the weak point turns with the champion. So if the target is on the front and they turn away, it might not hit the target and get triggered. Each time hitting the target would activate flat true damage. ( 20 + 15 x Level )
It'd increase skill rewards and skill cap a lot, and would add a whole new level of complexity and rewards for the players. And for the people playing against Vel'koz, it'd also offer a method of counterplaying the passive damage.