Lets start off with the traditional foil slot, which thankfully has only rares and mythics
Snapcaster Mage Snapcaster Mage turns the graveyard into a toolbox, effectively doubling the value of your best spells
Clavileo, First of the Blessed Yes, I play aggro vampire decks and Clavileo, First of the Blessed makes me happy since I really want the attacking creature to die so I draw a card and get a vampire that's stronger
These were generally cards that were seen to be too problematic when you always had access to them from the command zone (Rofellos, Llanowar Emissary is a great example, as it could consistently come out on turn 2, or even turn 1 with a particularly spicy hand!)
If you hover over the logo, it will tell you how many of each wildcard you need to finish the deck