Vorgansharax the green dragon

Lives in the North,
Ozark mountains Buhr Widu in the Bvoont forest Vfnir
Has caused untold damage including killing a number of Firbolgs
Jazjar Firebolg Druid, Circle of the Moon

Has a blue Slaad, (more if a Gray Slaad with magical gifts).  Xynicynct.
The Vfnir Druid and his Acolytes worshipers a combination of Vfnir and Picts.