The Max Potion (121 / 116) card can be found in the Plasma Freeze set.
Recently sold 3 times and based on those sales is worth around £18.34.
Currently, there are 4 open listings for this card on ebay.
This card sells in the range of £12.53 to £24.15, making it quite stable.
This Rare Secret card was illustrated by 5ban Graphics.