Thread Convergence

You create a complex array of magical threads that slice through a 20-foot-radius sphere centered on a point you can see within range. Each creature in that area must make a Dexterity saving throw. A target takes 4d10 slashing damage on a failed save, and its speed is halved until the start of your next turn. A creature takes half as much damage and doesn't have its speed halved on a successful save.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d10 for each slot level above 3rd.