Brilliant Ouroboros

You create a 10-foot-radius, 20-foot-tall cylinder of magical energy centered on yourself. The glowing image of an ouroboros appears where the circumference of the cylinder intersects with the ground. All creatures other than you within the cylinder must make a Dexterity saving throw. A creature takes 3d8 radiant damage on a failed save and half as much on a success.

You regain hit points equal to half the amount of radiant damage dealt by this spell.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d8 for each slot level above 3rd.