Some Tarot Deck are Dark in nature and instead of using them as a Divination Tool, they can control and manipulate you with you even knowing it. Simple example is Someone might become obsessive with it due to the Deck, it will make the User feel uneasy or insecure without it, in time every single little things in life they feel a need to consult the deck, the deck can compel them to do things against their will or nature, some weak will and mind will fall into depression, have suicidal thoughts or even to extent of killing themselves. In the Media globally, there are many reported, unreported or unsolved cases of unnatural death due to influence of Tarot.
As a Novice or Seeker many are solitary or without guidance and when things happen they do not have any help. I am not saying everyone will be harmed in such ways however the possibility is very high to the unknowing novice or seeker, thats the danger of Witchcraft and towards other kind of Spiritual Practices. Even for healing light work can become dangerous or cause harm to One who are not doing it right, instead of sending healing energy, they are sending bad vibe or even draining their own core energy that lead to the weakening of their physical selves.
So the use of Tarot should be exercise with care. Just like not every reader can use every decks that are available in the Market. Such danger lurking or exclusion clauses are unspoken just like the use of certain drugs, their side effects are not mention or just mention briefly in few words. To each it's own, ultimately is your own choice and doing, nobody is to be blame for your own choice or action, your actions only need approval of your own.
This is a new perception to me. Though maybe it's different with playing cards, but I've never felt the danger before.