For now he was sealed in a stone tomb, but Nimueh had overlooked that stolen magic would gradually over time return to its own master. So millenniums would go by. Arthur and his round table would pass into legend. Nations rose and fell and magic faded from the world. So that Nimueh gradually lost her powers. When the spells finally failed her, she began to age.
When the magic at last returned to Merlin, he used it to break free from Nimueh’s entrapment. Then returned the favour by trapping Nimueh in a spiders web. He would restore her beauty but then transformed her into tapestry. For eternity?
This story was jointly written with B Thornber.