Mystic Knights of Tir Na Nog

The Warrior of Temra (1x43)

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After suffering numerous losses, Maeve travels to the castle of her former teacher, Nemain, to unleash a powerful half human/half demon warrior named Lugad. The new warrior of Temra quickly earns victories for Maeve and Cathbad fears that not even the Mystic Knights will be able to defeat him.