Vilmar's Lava Beam

You create a concentrated beam of thick magma conjured from the earth that fires in any direction you choose within 60ft. 

A creature targeted by this spell must make a Dexterity saving throw. On a failed save, the target takes 12d10 Fire Damage. Half as much on a successful one.

Lava spills onto the ground creating difficult terrain in a 10ft radius for 1 minute. Anyone entering the space on their turn takes 6d10 fire damage.

Creatures that failed their save are stuck within this radius and will take 6d10 fire damage at the start of their turn if they remain. 

At Higher Levels. When you cast this spell using a spell slot of 8th level or higher, the damage increases by 2d10 for each slot level above 6th.