im not good with ideas and such but more or less after a certain elf trait (probably celestial or higher) you can take a decision to ascend from the mortal plane into whatever the elven equivalent of heaven is and become some sort of angel, god, higher form of life, etc.
mechanically, the character ascending would die and you would play as your heir, your dynasty would gain a bunch of renown (more can be aquired depending on how high your elf trait is) and your dynasty/house could obtain some type of modifier