She accompanied him on his world travels, learning his magical secrets and discovering sacred stones in Italy.
Tlachtga's name was attached to the Hill of Ward in County Meath, which was the site of prominent festivals in her honour in the Middle Ages.
According to some Irish lore, Tlachtga was raped by Simon Magus while her father was learning magic, and gave birth to three sons Dorb/Doirb, Cuma/Cumma, and Muach.
The triple birth is a common theme in Celtic mythology, and her death from grief and the construction of a fortress at her grave echoes the story of Macha.
The site was known in the popular culture of medieval Ireland as a place where Mug Ruith's flying machine roth rámach had been seen, and where the ard rí Ruaidrí Ua Conchobair had held a massive assemblage in 1168.