Vortex Grenade

You lob a tightly packed ball of void Light onto a hard surface within range and, upon impact, the ball bursts into a 10-foot diameter sphere of churning void Light, centered on the spot it hit the surface. All creatures in the area take 4d4 void damage, and for the duration, all creatures that start their turn within the area, or who enter the area for the first time on a turn, take 4d4 void damage. A creature that takes damage from this grenade must also succeed on a Constitution saving throw or be pulled back toward the center of the effected area.

Cantrip Upgrade. The damage dice increases when you reach levels 7 (6d4), 11 (7d4), and 17 (8d4).