Serialized and Special Rarity Cards There are cards that had special versions printed that wont be available in that form again, like a Japan showcase or Wilds of Eldraine's Enchanting Tales
Let me show you some of the great work Jung Park has put together: He has done many iconic cards like Chromatic Lantern and Skysovereign, Consul Flagship
Since Mishra renames the token copy, you can copy legendary Vehicles with this ability without the legend rule blowing one of them up
Booster pack contents vary, and specific cards, rarity pulls, pull rates, or complete sets are not guaranteed
Stun counters might be what you're looking for
It's not often that a common makes it onto these 'best of' lists, but Delver of Secrets is such a strong card that you should really feel blessed to see one when opening a pack