Vrigg's Lava Flow

Molten lava flows out of the caster's mouth, forming a 10ft line of magma. The magma does 2d8 damage upon first contact with a creature, and then 1d8 for every additional round the creature is in the pool. After four rounds, the lava cools and becomes harmless rock. If a creature in the area of effect succeeds on a dexterity save, halve the damage and remove the creature from the lava pool.

At 3rd level, the line's size increases to 15ft. At 5th level, the line's size increases to 20ft.