Soli

Soli (소리) or sound is what witches hear in their given immortal lives. The sounds are unique to every witch, from cries of revenge to cries of mischief, and correspond to their unique abilities.

Witches' Missions
Witches are born to hear a specific type of earthly desire, such as a desire for revenge or strength. They collect energy from those emotional moments once they go to the source of the soli.