Explosive Concentration

Prerequisite The ability to cast spells

When you lose concentration on a spell due to taking damage, the magical energy held inside your mind releases explosively. As a reaction to losing concentration, you can make a 15-foot sphere of purplish light. All creatures within that sphere must make a Wisdom saving throw. On a failed save, a creature takes 1d4 psychic damage per each level of spell slot of the spell that you were concentrating on. On a successful save, a creature takes half damage.
You can do this a number of times equal to your spellcasting modifier. You regain all uses on a long rest.