Lucent Singularity

You fire an erratic light in a 15-foot-radius sphere at a point of your choice within range of the spell. While the spell lasts, the area becomes difficult terrain for hostile creatures. At the end of the duration, this singularity explodes, and each hostile creature in the area must make a Constitution saving throw. On a failure, an affected creature takes 4d6 radiant damage. You can detonate this singularity at any time using a bonus action.

At Higher Levels. When you cast this spell by spending Mana points equal to a 4th-level spell or higher, the damage increases by 1d6 for each spell level above 3rd. When cast as a 5th-level spell or higher, this spell’s damage becomes luminary.