You don't have those individual elements....
Meaning that you wont' deal any extra damage because you don't have those elements...
You can make them twilight but not darkness or light, you're only allowed to use elements on your elemental tree.
So both advantages and drawbacks would have to be edited.
And 10% is a bit much, 5% is the only real way that it would be approved without having to like, activate MP each time you use that ability...