Board Thread:General Discussion/@comment-25926288-20151109132112/@comment-25926288-20151109164254

Nevermind, Nimue spilled the beans.

Nimue said that if she had Merlin's power she would give powers to others that deserved it. So perhaps she gave others magical powers and that's what starts the brand of magic that she uses that takes root in the Darkness in your heart and then they call it "Dark" magic.