WB Midrange is another deck that ports over well from pre-Shadows-over-Innistrad Standard. While it is often referred to as WB Eldrazi, and it does feature some Eldrazi, the bottom line is that this is a midrange deck that has good enough mana to support a few solid Eldrazi creatures.
Eldrazi Displacer and Thought-Knot Seer remain awesome in decks that can cast them. Modern staples from before the ban of Eye of Ugin, they have a high enough power and toughness that they’d be candidates for Standard even with lesser abilities. These cards hit hard.
Archangel Avacyn is the big addition. A flash threat changes the way that games are played. You could already attack with everything in some situations due to the presence of Eldrazi Displacer, but this just makes all combat a complete nightmare. In conjunction with the Displacer, Avacyn can be blinked out with the Avacyn, the Purifier trigger on the stack. All your creatures will once again gain indestructible, all of theirs will take 3 damage, and you will continue to crush.
Sorin, Grim Nemesis is the other big addition from Shadow over Innistrad. This planeswalker can completely take over a game. The minus is effectively Corrupt, taking down a huge threat and gaining you a bunch of life. If the card you’re killing happens to have toughness less than 6, then you still have a planeswalker ready to go. The plus ability is card advantage and a win condition all in one. A planeswalker on 7 loyalty that will eventually finish off your opponent (either through the damage or the card advantage) is tough to beat.
The removal also got a decent upgrade. Declaration in Stone isn’t at its best in a midrange deck, but it’s a 2-mana removal spell that kills everything, won’t let it come back, will sometimes be card advantage, and is the perfect sweeper against tokens. Anguished Unmaking is 1 mana cheaper than Utter End, which is huge when you have Thought-Knot Seer and Archangel Avacyn on your curve. The life loss matters, but the efficiency matters more.
WB Midrange and Control decks are going to be major players going forward in Standard, so you’d better be prepared to fight against the Eldrazi and Angel tag-team!