You can find older, unopened booster boxes, but expect to pay more than current releases
How to beat: Collect every One-Star, Two-Star and Three-Star Shiny Card in the Mega Shine expansion: Scyther, Pineco, Phantump, Trevenant, Charmander, Charmeleon, Ponyta, Rapidash, Slowpoke, Pikachu, Raichu, Electrike, Hawlucha, Gastly, Haunter, Zorua, Zoroark, Forretress, Dratini, Dragonair, Dragonite, Axew, Fraxure, Haxorus, Mega Charizard X, Mega Slowbro X, Mega Manectric X, Mega Gengar X, Mega Scizor X, and Immersive Shiny Mew
this is an extraordinary step, and one we are unlikely to repeat
Instant-speed pump spells are almost always the better option, as you can surprise your opponent during combat if they decide to declare blockers