The Reshiram & Zekrom GX (222 / 236) card can be found in the Cosmic Eclipse set.
Recently sold 8 times and based on those sales is worth around £41.34.
Currently, there are 9 open listings for this card on ebay.
This card sells in the range of £29.42 to £53.26, making it quite volatile.
This Rare Ultra card was illustrated by Naoki Saito.
The fact that it is a GX card makes it one of the more valuable cards.