Here's why:
* Low Print Run: This card was printed in very limited numbers, making it extremely scarce.
* Full Art Variant: The full art version is especially rare compared to the regular version of the card.
* High Demand: Due to its rarity and powerful abilities, Black Kyurem EX is highly sought after by collectors.
It's worth noting that other extremely rare cards from the Black & White set include:
* Full Art Black Kyurem EX (from the Black & White - Boundaries Crossed set)
* Full Art White Kyurem EX (from the Black & White - Boundaries Crossed set)
* Full Art Zekrom EX (from the Black & White - Boundaries Crossed set)
* Full Art Reshiram EX (from the Black & White - Boundaries Crossed set)
If you're looking for the rarest Pokémon card in the Black & White set, Black Kyurem EX (full art) from the Plasma Blast set is your best bet!