Dragon's Claw – Magic 2011 uncommon. The Darksteel "charms" have become a core set staple, with Dragon's Claw even cracking Standard play occasionally. In Magic 2011, Dragon's Claw features new flavor text from—who else?—the dragon-worshipping Planeswalker Sarkhan Vol.
Steel Overseer – Magic 2011 rare. In addition to pumping itself to monstrous proportions and refueling Triskelions in Magic 2011 Limited, Steel Overseer can partner up in casual with another artificial taskmaster, the modular-loving Arcbound Overseer, for extra counter-counting shenanigans. (Doubling Season would like to help too!)
Sword of Vengeance – Magic 2011 rare. The abilities granted by Sword of Vengeance echo the abilities of Akroma, Angel of Wrath. As the flavor text notes, we can't say for sure that it's the real deal. Still, this card does subtly imply that without her sword, Akroma would be a 4/6 with flying and protection from black and from red.
Temple Bell – Magic 2011 rare. You don't need us to tell you that Temple Bell is worth playing in a multiplayer game, do you? Of course not! But we do have one tip: if you yell "BONNGGGGGGG!" every time you tap it, you're probably not going to be invited back for the next game.
Angelic Arbiter – Magic 2011 rare. While it's always fun to play cards that affect everyone in a multiplayer game directly (who doesn't like giving everyone life with one hand and damage with the other?) there's something to be said about Angelic Arbiter's ability to change the way everyone plays. And that something is "keep a Safe Passage in reserve to keep the angel alive."
Hunters' Feast – Magic 2011 common. Historically, cards have tended to target either one player or all of them, with a few Fireball-style cards that cost mana for additional targets. Hunters' Feast takes a new path, letting you distribute life to only those players you deem worthy.
Blood Tithe – Magic 2011 common. In a multiplayer game, some people like to avoid making enemies. Which is only logical; if enough people want you dead, you're going to lose. But there's something to be said for smacking everyone in the face simultaneously while sitting back on your pile of stolen life. Consider working in a maniacal laugh, too.
Conundrum Sphinx – Magic 2011 rare. In a two-player game, Conundrum Sphinx potentially helps both the attacker and the defender. But with more people in the game, more people get to play along. Want to make everyone at the table happy? Start attacking!
Garruk Wildspeaker – Magic 2011 mythic rare. From his Planeswalker page: Garruk is a hunter to the core, a planeswalking predator whose hunting ground is the entire Multiverse. Gripped with a need to test his might and resolve against greater and greater challenges, his life's calling has become an endless hunt of the most ferocious and dangerous game that each plane can offer.
Chandra Nalaar – Magic 2011 mythic rare. From her Planeswalker page: There's no virtue in subtlety—at least not as far as the fire-mage Chandra Nalaar is concerned. Impulsive, passionate, and short-tempered, she's as ready to explode as the pyromantic spells of her ever-growing repertoire.
Liliana Vess – Magic 2011 mythic rare. From her Planeswalker page: Beautiful, cunning, and ambitious to a fault, Liliana Vess is quietly one of the Multiverse's most magnetic dangers. Liliana's dark charisma is undeniable—she's agelessly striking and sharp as the edge of a razor.
Jace Beleren – Magic 2011 mythic rare. From his Planeswalker page: Curiosity has always gotten the better of Jace Beleren. As a magical prodigy, he delved into lessons of sorcery deeper than the other students in mage academies, and succeeded to the point that even his instructors were suspicious of him.
Ajani Goldmane – Magic 2011 mythic rare. From his Planeswalker page: Ajani Goldmane is torn between his leonin ferocity and his sense of justice. He was born as an outcast within his own family, an albino leonin never accepted by the rest of his pride.
Manic Vandal – Magic 2011 common. Manic Vandal is very much like Uktabi Orangutan, except that it's red. Why does this ability get to be red? The flavor text suggests one explanation: "It's fun. He doesn't need another reason."
Mystifying Maze – Magic 2011 rare. How does Mystifying Maze compare to Maze of Ith? On Twitter, Aaron Forsythe said, "I don't think Ith did it right. His maze sent you home. This new one is one you actually get lost in for a while."
Teferi's Puzzle Box – Ninth Edition rare. Some people like to use cards like Howling Mine in their multiplayer decks in an attempt to make everyone at the table happy. You could do that. Or you could go the other way with a card like Teferi's Puzzle Box and actively mess with everyone at once! We're just saying.
Emblem of the Warmind – Future Sight uncommon. The little sunburst-like symbol in the upper left of Emblem of the Warmind is a special feature of the future-shifted frame, and it signifies that the card is an enchantment. The complete list is in this Arcana. And now that we're in the future, you can see those symbols in the card search in Magic Online.