You give the creature a choice to choose between itself or its allies. The creature gets to choose who to protect using the following options:

Protect myself: Searing rays of light fall down from the heavens, scorching those around the target. Each of the target's allies in a 30-foot cylinder centered on the target must make a Dexterity saving throw. A creature takes 8d8 radiant damage on a failed save, or half as much damage on a successful one.

Protect my allies: Searing rays of light fall down from the heavens, scorching the target. The target must make a Dexterity saving throw. The target takes 12d8 radiant damage on a failed save, or half as much damage on a successful one.

At Higher Levels. When you cast this spell using a spell slot of 6th level or higher, the damage increases by 1d8 for each slot level above 5th.