Lightdrinker
Able to absorb any light source within a 20ft radius and the area becomes magical darkness. Depending on the amount of light taken, is the amount of charge its given. When it reaches its maximum, it can't absorb any more light unless the cage is open. It will be able to do (# of charges)d10 radiant damage in a 5ft by 30ft beam with a DEX saving throw against your spell save