uncommon evocation fire 

Cast [>>] somatic, verbal

Range 120 feet; Targets 1 creature

Saving Throw Fortitude

You ignite a creature in lasting flames. The fire deals 4d8 fire damage and 2d6 persistent fire damage to the creature, which must attempt a Fortitude save.

Critical Success The creature is unaffected.Success The creature takes half damage and takes no persistent damage.Failure The creature takes full damage, as well as full persistent damage.Critical Failure The creature takes double damage, as well as double persistent damage.

Heightened (+1) Increase the initial damage by 1d8 and the persistent damage by 1d6.

Secrets of Magic, page 200.