The High Elves worshiped Fire and Mist as their faith.
The fire here referred to Phoenix Holy Fire.
Deep in the Phoenix Hall burned an inextinguishable golden holy fire. Legend had it that it was the last Fire Soul left behind by the elven ancestors after they failed to ascend to the heavens.
During the day, the elderly who had experienced the baptism of time and felt their souls falling into a void would throw themselves into the Holy Fire and use their souls and memories as fuel for the Holy Fire. Newborns would be sent to the Holy Fire to receive blessings at night. The experience and skills of the dead would warm the souls of these newborns, allowing them to obtain legacies from the past.
As for mist, it referred to the rich magical mist that perennially lingered near Ava State.