Packs with multiple rare cards do come up, but for the drop rate, take this update from Mark Rosewater
If it isnt a Pokemon, though, youre still one step closer to pulling one you need on your next turn because that card goes to the bottom of the deck
Copying any creature in your deck
Beyond that, you just need a Dragon, some treasure, and a draw spell or two to get going
The Saga mechanic from the upcoming set Dominaria seems like a great mechanic, but creates a new visual layout for the card the text box is over the card type, for example while it makes it more unique it also adds cognitive noise
Within the confines of a 40 card singleton deck is it harder to get the right balance of such cards and forcing it can lead to things like awkward mana curves