You channel devastating energy that rips apart, rending flesh, vaporising fluids and disintegrating bone and matter of a single creature you can see within range. A 5-foot wide line of air between the two of you whips about like a howling gale. This space becomes difficult terrain for any creature, regardless of abilities that might say otherwise. 

When you cast the spell, the creature must make a Wisdom saving throw. On success, the creature takes 6d6 force damage and the spell ends. On a failed save, and for as long as the spell is in effect, the creature is restrained, cannot move, be moved, or be moved by a spell that magically moves it (e.g. misty step).

On your next turn, you use your action to inflict 9d6 force damage on the creature. The creature may repeat the save for half damage. The spell persists for as long as you maintain concentration and spend your action each turn maintaining the spell. If you move willingly, you sever the link and the spell ends.

On your next turn, you use your action to inflict 12d6 force damage on the creature, at which point the spell ends. The creature may repeat the save again, taking half damage on success. If the target’s hit points are reduced to 0 by this spell, it is killed instantly, reduced to dust, and the spell ends. Once the spell is in effect, you do not need to be able to verbalise or see the creature, however total cover placed between you and the creature ends the spell.