You and your opponent have to reveal what these 15 cards are at the start of your match, but you don't have to make any swaps if you don't want to
You can only use each effect of "Radiant Typhoon Varuroon, the Vibrant Vortex" once per turn
Early on I was playing Thought Scour but I havent really had any trouble fuelling my Uros or finding spells to return with my Mystic Sanctuaries, and having to mill my opponent when I wanted to draw a card Id just Sanctuaried to the top occasionally felt awkward, so I moved to trying out Hieroglyphic Illumination instead and have been happy
You could even try and set up a combo where you cast something with an inflated mana value and then Counterpoint yourself a little inefficient for Plan A, but for a card you can already include just as a counterspell, its a cool trick for Counterpoint to have in its back pocket
This is one of the few boxes for 50 big ones thats actually worth your timeand your money
Lucario-GX, Greninja-GX, Zygarde-GX, Yveltal-GX, Naganadel-GX, even Volcanionand the majestic Arceusmust choose a side