Houndstone

Flip a coin until you get tails. For each heads, choose a random card from your opponent's hand. Your opponent reveals those cards and shuffles them into their deck.

ウラが出るまでコインを投げ、オモテの数ぶん、相手の手札からオモテを見ないで選び、そのカードのオモテを見て、相手の山札にもどして切る。