The "OH SH*T!" Button

You take a small detonater, and in a proclamation of your impending harm, click the button. Each creature in a 300-foot-radius sphere centered on yourself, including yourself and any party members, must make a Dexterity saving throw. A target takes 20d10 force damage and 20d10 fire on a failed save, or half as much damage on a successful one.

The explosion spreads around corners. It disintegrates all objects in the area that aren't being worn or carried.