I have the hardback and ordered the tarokka deck on the side which worked great. But you can also just use a regular set of playing cards.

Tarokka deck + hardcover CoS for 29$ https://www.amazon.com/Curse-Strahd-Adventure-Tarokka-Deck/dp/B09SK6D7TJ/ref=mp_s_a_1_2?keywords=tarokka+deck&qid=1669627096&sr=8-2