When Ailill Olom, King of Ireland, killed Aine's foster father, she made an enchanted yew tree beside the river Maigh in Luimnech, and put a little man it to play sweet harp music, to get her revenge.
Ailill's son and step-son were passing by the river, saw the tree and heard the sweet music coming from it. They argued about who would get the tree and the little Harper. When they couldn't come to an argeement, so they asked Ailill to settle the matter, and he gave them to his own son.
Because of the bad feelings over this judgement the battle of Magh Mucraime was fought and Ailill and all seven of his sons were killed. And thus Áine got her revenge.