Creeping Dark

There are nightmares that cannot be slain with fire, only truth.
You infuse yourself with dark energies and corporeal shadow, twisting your form into a terrible caricature. Until the spell ends, you gain resistance to bludgeoning, piercing, and slashing damage from nonmagical attacks, and you are heavily obscured. While you are under the effects of this spell, you can move through spaces as small as one square inch without squeezing. While in this form, you cannot take actions other than the Attack action. The first time you take the Attack action, you unleash a deadly spike of shadow against a target within your weapon’s reach in place of one of your attacks. Make a melee spell attack roll. If you hit, your target takes 4d6 force damage. Once you take the Attack action, or you take damage from a magical attack, the spell ends at the end of the current turn.

At Higher Levels: When you cast this spell using a spell slot of 4th level or higher, the force damage increases by 1d6 per spell slot level above 3rd.