Runciter was a Grand Maester during the reign of Viserys I Targaryen. He died in 112 AC and was replaced by Grand Maester Mellos.
In his records, he only cites a quarrel with King Viserys I Targaryen as the reason for Prince Daemon Targaryen's second exile.
1It is unknown whether "...sweet Matarys and Valarr, the Hand." indicates that Valarr was Hand, or that Matarys, Valarr, and an unnamed Hand of the King died during the Spring Sickness.