Those are all interesting, but if you roll a natural 20, you get to search your library for a card of your choice and then put it into play if its an artifact, or in your hand if its anything else
Cards that are banned may always be unbanned as new potential answers to problem cards are printed, however this has not yet happened
Most players aren't huge fans of the set, and I see where they're coming from
For the traditional foil cards, you have around a 14% chance to receive an uncommon Dracula series card and a separate 11% chance to receive a rare or mythic rare
Decks vary how many copies they play based on how reliably they want to have a copy once they hit seven mana, which is usually a question of how often they need that boost to win the game combined with how much they need to sacrifice to make sure they get that far
This land is ideal for decks that play only one color