The M Gengar EX (121 / 119) card can be found in the Phantom Forces set.
Recently sold 14 times and based on those sales is worth around £22.83.
Currently, there are 10 open listings for this card on ebay.
This card sells in the range of £9.81 to £35.85, making it quite volatile.
This Rare Secret card was illustrated by 5ban Graphics.
The fact that it is a EX card makes it one of the more valuable cards.