Youngest brother of Mesirnin Tasel, known as the Butcher of Quintus, who was almost as gifted a tactician as his father. His eminence was marred by only by his zeal, which proved his undoing. It was Casimo's decision to wipe out the entire Endros family, a direct contravention of the Bond of Lords. His decision led House Mortimas to switch allegiance and three other houses to withdraw their support and sit the war out—these factors served to extend and intensify the conflict.

During the Battle of Little Bridge, Casimo refused to fall back to higher ground and when enemy reinforcements arrived his men found themselves trapped. They were routed and Casimo, who refused to surrender, died at the hands of Besim Croyden, his former tutor.