what do you think TOMBS are? then relate that to ygo game. what does tombs stand for in this game? and what does tombs mean for vampires? what is the relevance of tombs for vampires' game play? srsly, dump people nowadays
I don't have the skill, but I assume the usefulness of sealed tombs is that it prevents either player from banishing cards from the grave. vampires have effects that banish their own cards, so stopping that effect allows them to use their card again from the grave instead of it being banished.
Also, the second responder: ( saying: "what do you think tombs are?"). You're a moron and actually the "dumb" (not dump) one. The TC asked a valid question.