Mana burn?

It would be cool if there was a champion that attacked another champion's resource for damage or utility. Kind of like a reverse .

He or she can even have some rivalry with Soraka if they turn out to be a support. maybe it can be an Assassin who's damage increases based on how much current mana/energy the enemy champion has? Just imagine being able to manipulate an enemy champion's mana before a team fight. Thoughts?