If you sink enough mana into its X cost, your opponents will either die or have no resources left to defend themselves, both on the battlefield and in their hand
There are dedicated agencies that grade cards, like Professional Sports Authenticator (PSA), and cards that have been professionally-graded command higher prices
What theme each booster contains is randomized, but each themed 20 cards will be sealed inside the pack and labled
Please see the pictures for the actual cards condition
I graded most of my valuable childhood cards and I only hit 2 Gem Mint 10s (1st Edition Jungle non-holo Snorlax, and 1st Edition Jungle Pikachu) most of the other cards came back 7s, 8s, and a handful of 9s
Once more speaking of power, this set might also get my vote for the best cards overall