Agents
The Morrígan
deity or supernatural figure in medieval Irish literature, frequently associated with war and destruction; she sometimes appears as part of a triad with Macha and the Badb; also associated with Nemain.
See also: Túatha Dé DanannTúatha Dé Danann (ass. time-frame: Túatha Dé Danann) – A common Irish designation for a group of supernatural or magical figures in Irish history, broadly equivalent to the aes síde. In the pseudo-historical tradition represented by Lebor gabála Érenn and other texts, they are presented and to some extent euhemerised as the pre-Christian people that conquered Ireland from the Fir Bolg and were later overcome by the sons of Míl (the Gaels).
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Arbuthnot, Sharon, “The phrase troig mná trogain in exhortative speech”, Studia Celtica Fennica 12 (2015): 5–20.  
abstract:
The phrase troig mná trogain appears in a number of Irish narrative texts from the medieval and Early Modern periods. It is clearly a reference to an undesirable experience. In light of this, there has been a tendency to interpret the phrase as meaning 'the pangs of a woman in childbirth'. Such an understanding does not seem justified, however, by the established semantic ranges of the words listed in DIL as trog, trogan or trogain. The purpose of this article is to reinstate Kuno Meyer’s century-old suggestion that the last element of this phrase is trogan 'raven' and to refine and build upon this, arguing that ben trogain is a kenning for the Morrígain in her bird-aspect and asking whether the first element of the phrase under discussion might be the word for 'foot'. Following this line of thought, it seems possible that the phrase in question is an allusion to that defining moment in medieval Irish literature when the Morrígain alights upon the dying Cú Chulainn, setting foot upon his spilt intestines.
Journal volume:  Studia Celtica Fennica: <link>
Epstein, Angelique Gulermovich, “The Morrígan and the Valkyries”, in: Greppin, John, and Edgar C. Polomé (eds), Studies in honor of Jaan Puhvel, 2 vols, vol. 2: Mythology and religion, JIES Monograph 21, Washington, DC: Institute for the Study of Man, 1997. 119–150.
Carey, John, “Notes on the Irish war-goddess”, Éigse 19:2 (1983): 263–275.