Sovereign Rune

The Sovereign Rune (覇王の紋章, Haou no Monshō, Supreme King Rune) is one of the 27 True Runes. It is the rune of Barbarosa Rugner.

Suikoden
The Sovereign Rune is a heirloom of the Rugner family that is embedded in the Dragon King Sword. The Sovereign Rune protects its user from all forms of magic, even that of magicial coercion, such as the Conqueror Rune and the power of the other True Runes such as the Gate Rune. It also enables its user to possess the form of the rune incarnate, the Golden Hydra.

The Sovereign Rune was last carried by Barbarosa Rugner; its whereabouts following Barbarosa's leap from Gregminster Palace are unknown.