Players are only allowed to have one copy of any card in vintage
If it's a permanent card and it's miscut so as to be twisted, it may be unclear if it's tapped or not
All are pretty relevant in the Standard format, so you'll probably recognise them from some of the best MTG Arena decks right now
All instances of the first chosen number on permanents, spells, and cards in any zone are the second chosen number
Rakdos Charm is cheap and instant artifact removal therefore trumping things like Torch Fiend in that role yet in its other, perhaps more situational uses the Rakdos Charm is not nearly as dull as a 2/1 for 2 offering you far more power
Gemstone Mine is unique in that it has a limited number of taps due to relying on mining counters that reduce every time it is tapped, it enters with three counters and gives one mana of any color when tapped