Arcane Detonation.

You cause an object to be imbued with arcane energy. As a bonus action, you can detonate the arcane energy. All creatures within a 5-foot-radius must make a Dexterity saving throw. On a failed save, the target takes 1d8 force damage, on a successful save you take half as much damage.

To detonate the user must say a synonym for detonation.

You cannot imbue living creatures with arcane energy.

The spell’s damage increases by 1d8 when you reach 5th level (2d8), 11th level (3d8), and 17th level (4d8).