Korthian Cypher Book

Korthian Cypher Book can be found on the corpses of all creatures in Korthia, more likely on rare and rare-elite enemies (for Conquering Korthia), and inside other Relic Fragment-containing lootables around the zone. Turn the item to Archivist Roh-Suir at the Reliquary of Remembrance of Keeper's Respite for 100 Cataloged Research and 50 reputation with the Archivists' Codex.