When you cast this spell you create a 1-ft geometric shape that later unleashes a blast of arcane energy. The shape glows dim sapphire that sheds low-light for 20-ft.

The shape can be held by other creatures after you create it. It remains active until dispelled or triggered. It is dispelled if it is not within 90-ft of you.

When you trigger the shape it explodes in a 10-foot-radius sphere, the sphere spreads around corners. All creatures in the sphere must make a Dexterity saving throw. A creature takes 1d10 force damage on a failed saving throw, or half as much on a successful one.

This spell's damage increases by 1d10 when you reach 5th level (2d10), 11th level (3d10), and 17th level (4d10).