Torrential Magma

A stream of molten magma erupts for the duration, from a point within range. Each creature in the immediate radius of a 40-foot-cone from the eruption point must make a Dexterity saving throw. A creature takes 20d6 Fire damage and 20d6 Bludgeoning damage on a failed save and falls prone. Or half as much on a successful one.

Until Round 5, creatures that fall prone in the magma must repeat the Dexterity saving throw at the start of each turn, suffering the same damage dice on a failure. Or half as much on a successful one, and they can spend half movement to move.

Each round you maintain concentration on this spell, the magma doubles its distance (*Not its radius) along a cylindrical path and any creature caught within the path repeats the Dexterity saving throw process.

Round 2. 80 feet. | Round 3. 160 feet. | Round 4. 320 feet.

Round 5. 640 feet. Damage on a failed Saving throw doubles, and creatures caught in the magma take a level of exhaustion each round continuing through Round 8.

Round 6. 1,280 feet. | Round 7. 1,560 feet. | Round 8. 3,120 feet.

Round 9. 5,280 feet and begins to cool. Creatures that navigate the cooling surface must make a Dexterity saving throw. A creature now only takes 10d6 Fire damage on a failed save and are considered Restrained. Or half as much on a successful one.

Round 10. Or whenever the spell is ended. The magma hardens into stone, and becomes Difficult Terrain. Any creatures trapped are petrified.