The Book of Covenant (colloquially, books) is an item that is required in order to upgrade the Castle. It is similar to the Arrow of Resistance, which is used to upgrade the Watchtower.


Books can be obtained by defeating Barbarian Forts on the map, in the Shop, or purchased for 10 Resource icon gem Gems each when attempting to upgrade the castle with insufficient books.

Item Description Gained from
Item Book of Covenant
Book of Covenant
Can be used to upgrade the castle.
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