Coselin is the seat of King Haakis Turensyn, ruler of the Kingdom of Rogna in the Elkyri Islands off the west coast of Ivinia. Coselin's impressive castle and town wall were financed through piracy are among the finest fortifications in Ivinia. From this stronghold, the kingdom's fierce and rapacious "sea-wolves" terrorize trading ships in the Sea of Ivae and mount viking raids on settlements along Ivinia's western coast.

The Coselin Castle article describes the settlement's history, government, religion, economics, and military forces. Includes a full description and color floor plans for the castle, along with color GM and player maps of the settlement. Brief descriptions are given for many local craftsmen and other locations in the town. The town's massive temple to Sarajin, the Ivinian god of battle and honor, is given an expanded treatment, with detailed descriptions, color floor plans, and adventure hooks.