Xephy's Cloying Pall

A tiny fragment of the Shadowfell leaks out from you. Each creature in a 15-foot cone originating from you is bathed in unnatural darkness that snuffs out non-magical sources of light. Creatures with Darkvision are unable to see in or through this darkness.

Strike A Match. The darkness lasts until the end of your next turn. Any magical light such as from Light, Dancing Lights or Produce Flame, that is in the area or enters it causes the darkness to dissipate.

Cold Shoulder. Creatures that begin or end their turn in this darkness must make a Constitution saving throw. On a failed save, a creature takes 1d4 necrotic damage. On a successful save, the creature takes no damage. 

This spell's damage increases by 1d4 when you reach 5th level (2d4), 11th level (3d4), and 17th level (4d4).