This is the parent of the Fire Rune. It increases the spell level of the Fire Rune by one and consequently adds a new level five spell: Final Flame, which like previous fire spells targets an enemy group, but this time with an hellish inferno, quickly annihilating entire enemy groups.
In the Dunan Unification War this rune could be forged onto weapons and would thus increase the damage output by a mighty 50%, if one was willing to sacrifice a Rage Rune for this.
Teo McDohl's officer Alen is the first who comes with this powerful rune as fixed equipment and in later games Camus, Estella and Konrad start with it as well. Being a higher tier elemental rune it is both very popular and rare. One of the these runes, which many players don't notice, is well hidden in Neclord's Castle and another one sometimes drops upon defeating Seed, who is using the power of the Rage Rune to strengthen his sword. - Celes