Balthac is a new immortal that the group had never heard of before. Apparently he was the legendary elven hero who was famous for slaying the red dragon named Calor. The original story says Balthac died in the battle as well.
However according to Kelter, an adventurer went back in time and rescued Balthac, and Balthac continued adventuring under another name until he became an immortal.
The head of his followers is Lady Lillith.
Balthac’s symbol is a dragons head being cleaved by a sword.