Additional ideas for modifying the spell.

Amplify + Increase Time = Brighter, basically a solid mage light.
Amplify + Decrease Time = Disable the light completely.

Reasons:
I like building with these in skyblock, but as I recently learned, they make poor blocks to use in a mob farm. Thus, having some way to disable the light generation would be really cool. I choose Increase/Decrease Time for the example because amplify/dampen are already used by the spell.