The ability to win a game with a card that should just be an insurance policy is a big part of this being a 10 on this scale too
Knowing which cards are valuable, in what grades, from which sets, requires serious study
Theme-wise, Threatening Shadow will subliminally feature scenes from the end game of the Pokemon Legends Z-A switch game (both the main storyline & Mega Dimensions DLC)
Chase Cards and Premium Artwork
Sob means that your opponent cant retreat during their next turn, and Torrential Pump offers an extra 120 damage to inflict on a Benched Pokemon in return for 3 Energy
I also love the fact that, against all odds, the trippy and vibrant color scheme has also made Seismitoad #105 an incredible chase card, sitting as the second most expensive Pokmon card of the expansion