Dragons, while powerful, usually come in small numbers because their average casting cost is much higher than a traditional aggro decks curve
and carried anywhere, anytime
Perhaps if it cost five to cast and five to active it would have been fair, but at three to tutor (Tinker) and zero to activate, it was completely abusive
I sure as hell don't know all of them
This is very much still the case now that the set is being revealed, and it may feel like a huge departure for Magic: The Gathering expansions after the likes of Bloomburrow, Duskmourn, or Tarkir: Dragonstorm
Though there are ways to guarantee getting hold of certain cards in products such as Starter Decks, for example, which are pre-constructed and always have the same selection of cards but for the most part, players will be at the whim of chance when opening a booster pack