Melusine is an old and powerful ekhidna living in a large complex of caves near the village of Svorlag, located in the Skellige isles. It is presumed that a cult once worshipped Melusine as evidenced by the large winged statue located in the caves beneath the mountains which she inhabits.
I... I saw a shadow... Great wings, like a cloud passin' o'er the sky. Then I heard him scream.
— Britt of Svorlag
In the mountains near the village of Svorlag in Skellige lies an enormous complex of caves. For many centuries they were given a wide berth on account of the bloodthirsty ekhidna known as Melusine who had made them into her lair.
Melusine was a beast so powerful some islanders worshipped her as a semi-divine being. The witcher, however, harbored no such delusions. He knew she was an extremely powerful monster – but a monster all the same. This meant she could be killed. To do so, he would need the highest quality bolts, a solid silver blade – and a steady hand.