This Rune is combination of the all of the Nero's seven deadly sins symbol as it appeared to like emojis. When NeroLuna unleashed the true power, this Rune will appear, spin itself slowly like wheel, and Nero's final form revealed. Each symbol represent seven deadly sins and they all represent power and skills what NeroLuna using. Look at the chart here for more details.

This Rune also use to summon NeroLuna as well. According to the ancient legend:
"if you desire for the power of the black moon devil, you must drew the rune at black moon. Then offer the dead beast on middle of the rune. Then show your darkness within you and chant them out. Then black moon devil will appear..."