You see, Painful Truths can act just like Ancient Craving for one less mana, as long as you spend black and 2 other colors on it
But for those looking for condensed advice: the ingredients of truly fierce competitive decks are infinite combo pieces, tutors to find them quickly, resource acceleration (mana rocks) to cast all those cards faster, and cheap interaction to stop opposing combos developing
Rarity Ultra rares, alternate arts, special illustration rares, and limited print cards tend to hold more long-term demand
These errors are especially rare so much so, in fact, that the seller of the card admitted to the price being a placeholder to draw attention to it
Take, for example, the Japan-exclusive High Class Pack Shiny Star V (a mouthful, to be sure), which features a large amount of reprints
its capable of ending games as early as turn two because of how absurd the value can get, as long as you build in ways to break it