The Darkrai & Cresselia Legend (100 / 102) card can be found in the Hs Triumphant set.
Recently sold 17 times and based on those sales is worth around £32.71.
Currently, there are 6 open listings for this card on ebay.
This card sells in the range of £23.83 to £41.59, making it quite stable.
This Legend card was illustrated by Shinji Higuchi + Noriko Takaya.