In the Year of Rogue Dragons, 1373 DR, Ilvarthaele was selected by the High Heralds to join them as a High Herald herself. She was also permitted to establish a new High Herald office, that of the Silver Stag, which she based in the Stormspire in the town of Songhal in Impiltur near the end of that year. This was the first time a new High Herald post had been created in the lands around the Sea of Fallen Stars since the Heralds had been founded in the Year of the Watching Helm, 992 DR.
Ilvarthaele was charged with supporting the practice of heraldry in the lands of Impiltur, Thesk, Damara, and the independent cities of northeast Faerûn. She was also tasked with maintaining and administering heraldry in lands east of the Inner Sea.