Frost Against the Hilt by Sarah Woodbury

Love, magic, faith. All roads lead to Camlann as Arthur gathers his men for a single battle—a final great contest against the full might of Modred and his Saxon army. Wales will win all or lose all in one last throw of the dice.

Frost against the Hilt is the fifth and final installment in the Lion of Wales series.

Complete series reading order: Cold my Heart, The Oaken Door, Of Men and Dragons, A Long Cloud, Frost against the Hilt.