Lost Art
From Plarium Games Wiki
Lost Arts enable access to new units, buildings and fortifications, as well as enhancing the performance of units. Buildings will improve production, units will gain strength and fortifications will enhance the castles integrity by adding to its defence bonus.
Discovery
Discovery, or mastering a Lost Art, requires building the House of Scrolls, which enables the Scribe to decipher scrolls at the rate of one per day. After obtaining a complete a set of scrolls, the Lost Art is then mastered by using resources.
Upgrades
Lost Arts can be upgraded using resources, each level reqires a higher value of resources, and takes a longer to master.