"Silver Moon Crystal Power" is a light-based/energy-based attack used by Sailor Moon in the anime and Eternal Sailor Moon/Neo-Queen Serenity in the manga and the Crystal.
Manga and Crystal[]
In the manga and the Crystal, during the Sailor Guardians' final battle with the Dead Moon Circus at Elysion and after Super Sailor Moon to lend her friends' strength from their planetary castles into her Holy Moon Chalice to become Eternal Sailor Moon as her powers are closest to the powers of Queen Serenity according to Diana, as it is said that Eternal Sailor Moon to her friends the Sailor Princesses to send their strength to her Eternal Tiare as she shout of this attack to change her Silver Crystal into the shape of the lotus.
After the defeat of Queen Nehelenia, Neo-Queen Serenity used the same attack to awaken the Amazoness Quartet and turn them back into the Sailor Quartet. She did not call out any attack name or phrase when she performed it though.
Anime[]
This was Sailor Moon's final attack in the anime. She attempted to use this to turn Sailor Galaxia back to normal, but it was unsuccessful.