Well, considering cards are made of paper, they are all flammable. They also make flash cards, which burns instantly. Or are you looking for something to coat the card in so the outside burns but the card remains intact?
First off, this should be in the cardistry section. Second, if you're new, don't start with dnd. And kevhonline has some cuts on his channel. ( by the way, I'm not really a flourisher, this has been posted several times)