Oathmark: Battlesworn - Rules of Play says:
This supplement for Oathmark: Battles of the Lost Age contains rules for adding elite units to your armies and charting their progress from battle to battle. Will they grow even more powerful as they gain renown, or be broken in the face of tremendous odds, perhaps someday to be reformed when their kingdom needs them most? Also included are rules for rivers and boats as well as campaigns, featuring all-new scenarios that will give your battlesworn the chance to lead their kingdom to new heights of power and prestige.