Combustive Pitch

You spray highly flammable tar from your hands, covering the ground in a 20 ft. square in fron of you. Creatures in that square must make a Dexterity saving throw. If a creature fails, their speed is reduced to 10 ft., and they are considered to be ensnared in the tar. An ensnared creature may use it's action to try to free themselves by making a Dexterity saving throw against your spell save DC.

If the Tar is ignited by fire, all creatures within it must make a Dexterity saving throw, taking 3d6 damage on a failed save, and half as much damage on a successful one.