This means that they can be cast with only generic mana, so you dont have to worry about the colors available to you when you cast them
Cards like Black Lotus and the rest of the Power Nine dont really have any business being reprinted
You'll be able to look at the top card of your library at the beginning of each of your upkeeps, but you can never put it into your hand this way, even if it's a creature card with no creature type
Sometimes, though, you cast a Halana and Alena, Partners on turn three, and your opponent doesn't have removal
It was an interesting time for Arena, especially with Jumpstart: Historic Horizons
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