Pyrefly Memorial

Lands observing this Law arguably don't have an afterlife. Instead, the souls of the dead shatter, each fragment becoming a pyrefly. When there are enough pyreflies in the area, fiends can begin to manifest. When killed, fiends become pyreflies again.
Law originates from Final Fantasy X and Final Fantasy X-2. We've seen Anima kill fiends that break into pyreflies, and seen pyreflies become fiends on Mt. Gagazet. Yuna said that the fiends are because of summoners and their guardians who died on Gagazet, and their frustration turned them into fiends. I think Lulu said something about that as well at one point.