Arms of Hadar

1st-level Conjuration

Casting Time: 1 Action
Range: Self (10-foot radius)
Components: V, S
Duration: Instantaneous
Spell Lists: Warlock

Invoking Hadar, you cause tendrils to erupt from yourself. Each creature in a 10-foot Emanation originating from you makes a Strength saving throw. On a failed save, a target takes 2d6 Necrotic damage and can't take Reactions until the start of its next turn. On a successful save, a target takes half as much damage only.

Using a Higher-Level Spell Slot:  The damage increases by 1d6 for each spell slot level above 1.

Source: PHB'24, page 243