Fire Rune is a skill located in the Mages Guild (which can be found in the Guild skill tree). Fire Rune is a base skill, and can be morphed into Volcanic Rune
or Scalding Rune
Fire Rune deals the following types of damage: Flame Damage. Which means that it gets buffed by the following blue champion point trees: Elemental Expert, Elf Born, Master at Arms, Spell Erosion. Also the following red champion point trees protect against this skill: Elemental Defender, Iron Clad.