Background
Morrigán means “phantom queen” and the Morrigán in Irish Mythology was a deity who could change shape and would influence the outcome in battles by playing with armies psychologically. Rather like Dionysus in Greek myth, the Morrigán could embody the darker side of nature, and work through alternate means, whether through drink or metamorphosis.

The Morrigan is a goddess of battle, strife, and fertility. She sometimes appears in the form of a crow, flying above the warriors, and in the Ulster Cycle, she also takes the form of an eel, a wolf, and a cow. She is generally considered a war deity comparable with the Germanic Valkyries, although her association with cattle also suggests a role connected with fertility, wealth, and the land.

Tales of the Morrigán
One tale of the Morrigán’s changing appearance concerned Cúchulainn. She appeared to the hero in the form of a beautiful young girl and declared her love for him. But he spurned her advances and in revenge she attacked him, first as an eel, then as a wolf, and then as a heifer. Cúchulainn overcame her and in her exhaustion she appeared to him as an old woman milking a cow. She gave him milk and he blessed her.

The Morrigán also represented sexuality, and she ritually mated with Daghda astride a river, with one foot on either bank. She also possessed herbal magic and used it to cast spells. She turned Odras into a pool of water as Odras’ bull had mated with the Morrigán’s cow.

Conclusion
The Morrigán had close associations with magic and death and her dark nature was a danger to her enemies.