Crawling Magma

You reach into the ground, and with an open claw, slash forward. You create magma in a 30 ft long 10 ft wide line in front of you that lasts until the end of your next turn, dealing 3d6 fire damage, or half as much on a successful dex saving throw. If a creature starts their turn in this area or enters this area on their turn, they take 3d6 fire damage.