It’s not a very clear hint, but it gives a huge hint as to its use.
Lightsworn Sanctuary fixes a key vulnerability of Lightsworn Decks: the risk of getting the wrong cards in the Graveyard.
Source:
Press Release
[TCG] A Hint about Lightsworn Sanctuary
By NeoArkadia
NeoArkadia
NeoArkadia is the 2nd Number of "The Organization" and a primary article writer. They are also an administrator for the forum Neo Ark Cradle.