Ubtao

Ubtao the Deceiver
During the events of the Dawn War, when the gods fought the primordials for Abeir-Toril, the primordial Dendar the Nightserpent swallowed the sun creating an ice age. Another primordial known as Ubtao the Deceiver betrayed the other primordials to the gods, defeating them. As reward the gods gave Ubtao the lands of Chult and promised not to influence them so long as he guarded the doors that imprisoned Dendar beneath the Peaks of Flame.