Tolbin's Tenebrous Trap

The caster creates a 20 foot radios dome of darkness that functions similarly to the Darkness spell  with the added benefit of the dark tar like substance clinging to targets within it's radius. Any creature other than the caster caught in the black sticky miasma must make a Dexterity save or be caught in the dark interior. Any creature other than the caster that enters the area on it's turn or begins it's turn there must make a Strength saving throw or be Blinded and restrained. Any fire cast within or at the area ignites the substance causing 2d4 fire damage in addition to other damage. The tar like darkness burns away immediately ending the restrained and blinded conditions. Objects or creatures that took the initial 2d4 fire damage take that damage again on subsequent turns until they take an action to put it out.