Black Cards are focused on sacrificing your own creatures and spells and then allowing you to search your deck for specific cards needed for combos
Razaketh, the Foulblooded Well, we know the last of the four Demons Liliana will have to kill will (likely) be a 9-mana 9/9 Demon
Stripping away Hexproof and Indestructible not just from opposing creatures, but all opposing permanents allows you to circumvent many difficult to answer pemanents, including Theros gods like Xengaos, God of Revels, pesky protection cards like like Darksteel Plate, and shielded lands like Lotus Vale
There have been plenty of alternate win condition cards in Magic: The Gathering before, but they usually take a lot of time and effort to pull out, outside of really cheesy combos
Loosely packed cards - real booster packs are sealed tight around the cards, with almost no room for movement
You can't pay a gift cost more than once