The Dusknoir (104 / 101) card can be found in the Plasma Blast set.
Recently sold 2 times and based on those sales is worth around £16.70.
Currently, there are 2 open listings for this card on ebay.
This card sells in the range of £16.55 to £16.85, making it very stable.
This Rare Secret card was illustrated by Ayaka Yoshida.