Betrayer Gods

The Betrayer Gods are the Creator deities who chose not to fight against the Primordials during the Founding. Vecna is also typically grouped with the Betrayer Gods, despite not being a Creator.

The Founding
The gods who brought life to Exandria are called Creators. When the Primordials came to retake the world during the Founding, the gods disagreed on their course of action. Those who would later become the Prime Deities wished to fight back against these forces. The Betrayer Gods preferred instead to let the world fall into chaos so they could start again elsewhere and left their creations behind. The Prime Deities gifted the people of the world with arcane magic so they could protect themselves without the direct aid of the gods. With this gift, the people of Exandria not only destroyed the Primordials but banished the Betrayer Gods to other planes that would serve as their prisons. The banishment was so profound that the Betrayer Gods could not lend their power to mortals.

The Age of Arcanum
The prevalence of arcane magic gave rise to the Age of Arcanum, during which the people of Exandria became arrogant and challenged the gods. Inspired by the ascension of The Raven Queen, Archmage Vespin Chloras, seeking power, released the Betrayer Gods from their prisons. However, the long imprisonment had twisted the deities who had once built the world, and they now sought to corrupt and destroy it. They betrayed Chloras, enthralling him, and built the dark city of Ghor Dranas from which they could wage war on Exandria. They began with a brutal attack on Vasselheim, which survived, albeit with heavy casualties, thanks to the intervention of the Prime Deities. However, the damage was much more far-reaching; seeing the destruction in Vasselheim, the people of Exandria began building weapons and magical items that could kill gods and went to war.

The Calamity and the Divergence
The Calamity was a war between the Prime Deities and Betrayer Gods, and many of their mortal creations perished in battle. The world they had once created together was permanently scarred, and only a third of the population survived. The Betrayer Gods were banished again to their realms, but the Prime Deities chose to leave as well, believing their involvement in Vasselheim had been a precipitating factor. They implemented the Divine Gate, which prevented all of the Creators, Betrayer and Prime alike, from physically entering the Material Plane. This event would later be known as The Divergence.

Vecna
Vecna was a mortal archmage who became a lich during the Age of Arcanum. He and his former lieutenant Kas the Bloody-Handed destroyed each other in battle prior to the Calamity. For centuries, he gathered followers, and ascended to godhood during the time of Vox Machina. Vox Machina sealed him behind the Divine Gate shortly afterward.

Deities
All of the Betrayer Gods are evil-aligned.

Trivia
The Pantheon of Exandria is taken from the Dawn War Deities, with the addition of Sarenrae, a Pathfinder deity. The Betrayer Gods are the evil-aligned deities from this pantheon.