He and his brothers
Mac Cecht and
Mac Gréine killed
Lug in revenge for their father. The three brothers became joint
High Kings of Ireland, rotating the sovereignty between them a year at a time, covering twenty-nine or thirty years depending on the source consulted. They were the last kings of the
Tuatha Dé Danann before the coming of the
Milesians. Mac Cuill and his brothers treacherously slew
Íth, prompting his nephew
Míl Espáine and his sons to invade Ireland for revenge. During the battle against the Milesians, Mac Cuill was slain by
Eber Finn. ==References==