source wowtcg forum:
Official List: Core Legal Cards
Currently the following cards and sets are legal for Core:
Worldbreaker Block
Sets: Worldbreaker, War of the Elements, Twilight of the Dragons
Crafted: (5) Crafted 1-12
Badge: (5) Badge 1-12
Special Releases: Class Starter Decks (2011)
Promotional: Cataclysm Collector's Edition, (5) Holiday 1-5, (5) Class Promo 1-13
Aftermath Block
Sets: Throne of the Tides
Crafted: (6) Crafted 1-3
Promotional: BlizzCon 2011 Card
Badge:
(5) Badge 1-12: Amulet of Dull Dreaming, Celadon Pendant, Pendant of Quiet Breath, String of Beaded Bubbles, Band of Bees, Band of Secret Names, Ring of the Battle Anthem, Twined Band of Flowers, Bedrock Talisman, Core of Ripeness, Fluid Death, Soul Casket
Crafted:
(5) Crafted 1-12: Crawling Claw, Scimitar of the Sirocco, Staff of Ammunae, Chalice of the Mountain Kings, Clockwork Gnome, Staff of Sorcerer-Thane Thaurissan, Queen Azshara's Dressing Gown, Bones of Transformation, Highborne Soul Mirror, Snaggle, Soggypaw, Violet Proto-Drake
(6) Crafted 1-3: Fossilized Hatchling, Fossilized Raptor, The Innkeeper's Daughter
Promotional:
Cataclysm Collector's Edition - Jacob Blackcrest, Kirox Butcherblade
(5) Holiday 1-5: Red Rider Air Rifle, Kwee Q. Peddlefeet, Krazal the Eggregator, Searing Scorchling, Swift Brewfest Ram
(5) Class Promo 1-13: Bolvar, Highlord of Fordragon Hold, Burly Berta, High Commander Halford Wyrmbane, Jaina, Lady of Theramore, Leeroy Jenkins, Deathlord Jones, Garrosh Hellscream, Plainswatcher Taro, Saurfang the Younger, Kor'kron Warlord, Thrall, Warchief of the Horde, Babagahnoosh the Grumpy, Fordragon Hold, Kor'kron Vanguard
BlizzCon 2011 - Hogger Monster Hero