Nova Subrace

Ability Score Increase. Your Wisdom score increases by 1.
Shattered Star. Starting at 3rd level, you can use your action to unleash the destructive energy within your husked self, causing your body to detonate.
Your transformation lasts for 1 minute or until you end it as a bonus action. When you first transform, each creature other than you in a 10-foot radius centered on you must succeed on a Dexterity saving throw or take a number of d6s of fire damage from the explosion equal to your proficiency modifier.
During the transformation, you shed bright light in a 60-foot radius and dim light for an additional 60 feet. Your body becomes unstable. Once per round, when you hit a creature with a melee attack, or are hit by one, your body detonates. Each creature in a 10-foot radius centered on you (you included) take radiant damage equal to your proficiency bonus.
Once you use this trait, you can't use it again until you finish a long rest.