Queen Medb held meetings with the families of those slain by Cú Chulainn to seek revenge for the deaths of their loved ones. She sent the three daughters of her magician Calatin to Alba to learn the magical arts. They eventually returned and could summon up illusions of battle hosts with their new found skills.
As Medb’s forces marched toward Ulster, King Conchobar did not want Cú Chulainn to fight since if he fell, the land would be forever cursed. Conchobar, therefore, ordered the women, the bards and the poets to distract him to keep him away from battle.
The three daughters of Calatin appeared and created an army out of grass, thistles and withered leaves. The Druids convinced Cú Chulainn that this was an illusion to stop him from running into battle .Conchobar moved him to a magical where no sounds from the outside world can be heard.
The daughters then created an illusion of a vast army surrounding the valley, fires burning and women screaming and crying. The magic was so powerful it reached into the valley. Cathbad the Druid managed to calm him down and convince him that it was another illusion.
Finally, one of the daughters of Calatin shapeshifted into a lover of Cú Chulainn and begged for Cú Chulainn’s help. He rode out to find this invading army, despite several omens. Three old crones (the Mórrígan) were roasting a hound on rowan spits and offered him meat. Cú Chulainn refused to eat the flesh of his totem animal. They persisted saying he was too proud to eat their humble food, but will feast on the foods of chieftains and kings. Cú Chulainn eventually and was paralyzed in the left side of his body.
A prophecy predicted that the spears Cú Chulainn carried would each kill a king. Three Druids were sent to ask for the three spears since it was considered unlucky and dishonourable to refuse a request from a Druid. The first Druid demanded his spear or he would satirise him. Cú Chulainn flung it at the Druid and killed him. However, Lugaid son of Cúroi, took the spear from the Druid's body and slew Laeg the charioteer of Cú Chulainn. The second Druid said he would satirise the whole of Ulster if he was refused the second spear. Again he flung the spear into the Druid's head and killed him. Erc the King of Leinster snatched the spear, and killed Cú Chulainn's horse the Gray of Macha with it.
The final Druid said “Give me your spear or I will satirise your Clan.” Cú Chulainn flung his last spear into the Druid's heart and killed him. Lugaid again reclaimed the spear, but this time flung it at Cú Chulainn himself. Before dying Cú Chulainn bound himself to a standing stone by the lakeside so he could die standing up like a warrior. His face became as white as snow and the Morrígan appeared as a crow and perched on his shoulder as he died. Thus the prophecy of the spears was fulfilled for Laeg was king of the charioteers, the Gray of Macha was king of the horses, and Cú Chulainn was king of the champions.