Pantheon
The Triad is a group of three gods consisting of Lathander, Pölark, and Titania. They were formed directly after the Second Agon in response to the other five remaining primordial gods being killed. The Triad believes that all Current Gods except themselves are usurpers and murderers, and due to them being originally mortal do not deserve to have the title of god, though this belief does not necessarily extend to their followers.
Those following the Triad usually do so because they are technically the oldest still-living religion, despite being just over 200 years old. Their traditions source from them being the only three primordial gods still remaining, and so they have drawn many of their followers from people seeking the older ways.
The Triad begun the Time of Strife after the Second Agon by going to war with the magic cities of Arkas and Sigil. The gods blamed these cities and their studies of Animus and Agons as the reason why so many of their siblings had died. As soon as the Agon finished and the Triad shed their mortality once more, they focused all of their destructive power on Arkas in the Sara Dominion, causing the Veil around it to buckle under the weight of the magic and kill everyone in the city before utterly destroying it, turning those who tried to teleport away insane. Sigil, in East Faerûn, thanks to having obtained the animus of The Wanderer, was able to construct a Godflow Engine and teleport their city into the Astral Plane. When the Triad got around to attempting to destroy Sigil, it was just teleporting away, and as such their destruction left a devastating mark on the land around the city, now known as Landfall.