There are three types of Crest Stones, which can be used in "Ancient Kingdom Crests".

The three types are: [Crest Stone of Establishment], [Crest Stone of Revival], and [Crest Stone of Ruin], and it is used to unlock the crests and change the crests.

Crest Stone of Completion is used for protecting 6 or more crests. It's also used for changing crests.

※ The cost for crest change will vary depending on how many locked crests you have.