Corrosive Sphere

You create a globule of acid and hurl it at a point within range, where it explodes in a 20-foot-radius sphere. Each creature in that area must make a Dexterity saving throw. On a failed save, a creature takes 10d4 acid damage and another 5d4 acid damage at the end of its next turn. On a successful save, a creature takes half the initial damage and no damage at the end of its next turn.

Overcharge Tech. When you cast this power using a tech slot of 5th level or higher, the initial damage increases by 2d4 for each slot level above 4th.