[@thewizardguy]
I'd say light is the easiest to abuse. Limitless application. Corban does it to some degree with carbon, except the difference is the scope. Corban just uses carbon in ways lots of people might not expect. Not quite the same as just overstretching power but yields similar results.

Edit: Using water to control other char's blood is generally paramount to character control and autoing. Which is why that gets such the bad rep it does in combat