A narrow black beam emanates from your hand at a point of your choosing you can see within range. A roiling dark mass of flames roars to life and churns on itself, devouring almost all nearby light, creating a Darkstar. White hot flames lash out from its surface periodically and are quickly drawn back into the mass, disappearing completely.   The Darkstar itself encompasses a 10 foot radial sphere, centered on the point you chose. This radius wraps around corners. The Darkstar itself is completely dark and snuffs out any light, magical or non-magical in its radius, and there is a 20 foot radial dimming effect around the Darkstar. It emits a constant low roar of flame. As a consequence of absorbing light, it also blocks vision, while simultaneously distorting or warping the dimmed area surrounding it, imposing disadvantage on ranged attacks through the dimmed space. Any physical projectiles, which are not being worn or carried, that would pass through the Darkstar itself are destroyed on contact. All flammable, non-magical objects in its area of effect are ignited.   On each of your following turns, while you are concentrating, you may expand the radius of both the Darkstar and the dimming effect by 5 feet as an Action.   Any target inside the Darkstar's radius is blinded and deafened by the star itself and its interior is treated as difficult terrain because of the torrent of black flames.   Targets that enter the space of the Darkstar for the first time or start their turn there must make a Constitution Saving Throw against your Spellcasting DC or take 6d8 Fire Damage. Each turn they start inside the Darkstar, they must make another Constitution Saving Throw against your Spellcasting DC. For each turn after the first, apply an additional stack of 2d8 Fire Damage added onto the base damage, reaching a maximum amount of 12d8 Fire Damage per turn after 3 turns inside the Darkstar. Successful saves only take half damage.   When the spell ends, either because you dismiss it or your concentration is broken, it leaves a blackened, charred surface where it once was, covered in chaotic spiral scoring.