It is unknown whether Hidden Ability percentile increases (e.g. "Agility: 4.50%") multiply with or add to Crest percentile increases.
Adding Hidden Abilities Edit
Players may utilize items called Sparks to bestow equipment with a random selection of predetermined stat boosts. Each Spark, when right-clicked and supplied with a target equipment item, will randomly roll 0 to 3 stat boosts depending on the kind of Spark used, overriding the previous Hidden Ability set if one exists.
If the previous Hidden Ability set was preferable to the new one, the player may pay a fee (of ingame currency) to restore the previous Hidden Ability. If the player chooses not to, or cannot afford to do so, the new Hidden Abilities will remain.
This fee is about 10 gold for the lv. 24 Ancient Set. Whether it increases with higher-level equipment and Sparks is uncertain.[need higher-level player to check]