Comes a Horseman (1) - S5.E12

MacLeod knew him as Melvin Koren, a desperado who left a trail of death and fire across the Old West, but Cassandra remembers him as an evil far older. He is Kronos, leader of the Four Horsemen, mounted Bronze Age raiders who murdered, raped, and pillaged their way across two continents. Never was a band of Immortals more cruel or more feared. He destroyed Cassandra's people and she's been hunting him across the millenia. But Kronos has a different target now -- Methos.