[6] In the Táin Bó Cúailnge, after the Ulstermen have roused from their debility, he and Conchobar mac Nessa rescue eight captive Ulster women from eight men of Ailill and Medb's household at Áth Féinne.
The first is Conganchnes mac Dedad, who seeks revenge for the death of his nephew Cú Roí, and who has skin like horn, which no weapon can pierce.
Celtchar offers him his daughter Niam in marriage, who discovers that Conganchnes can only be killed by hammering red hot spits into the soles of his feet.
Celtchar finds an alder log, hollows it out so his arm will fit through it, and boils it in honey, grease and herbs until it is tough and supple.
It was found as a pup inside Conganchnes's burial mound, and would only let Celtchar handle it, until one day it escaped, and became a menace to the cattle and sheep of Ulster.