Flesh to Flame

The arm used in the spell's casting begins to glow red hot, its skin bubbling as if it were about to burst. Make a melee spell attack against a creature you can reach. On a hit, the creature takes 6d6 Fire damage as your arm explodes. 

Additionally, each creature in a 60-foot Cone originating from you makes a Dexterity saving throw, taking 6d6 Fire damage on a failed save or half as much damage on a successful one. The creature hit by the melee spell attack automatically fails the Dexterity saving throw.

After casting the spell, the area on your body where your arm once was slowly regrows your arm and continuously emits steam. After completing a long rest, the arm consumed as the material component of this spell fully regrows and your body ceases to emit steam.

Using a Higher-Level Spell Slot. The damage for the Attack and Cone both increase by 1d6 for each spell slot level above 4.