Unlocking cards faster:
Note: A cooperative friend is required. Start a Free For All Duel, set it to private, and invite your friend to the one on one duel. When your friend enters, begin the duel. The winner will get a card. After you or your friend wins, start over. Repeat this for a full deck.
Arcane Knowledge - Unlock twelve cards for one deck.
Artificer - Win a game with Tezzeret's deck.
Dragon - Win a game with Sarkhan's deck.
Duelist - Win five matches online.
Evil's End - Complete the Archenemy campaign.
Final Exam - Defeat Karn in a campaign game.
Gather Your Allies - Host an Archenemy match online with two human teammates.
Hammer - Win a game with Koth's deck.
Hot Shot - Win a game with Chandra's deck.
Magic: The Puzzling - Solve a challenge.
Metalcraft - Control three artifacts in a game.
Mind Sculptor - Win a game with Jace's deck.
Mythic - Cast a mythic rare spell in a game.
Predator - Win a game with Garruk's deck.
Puzzling Master - Solve fifteen challenges.
Savior - Win a game with Nissa's deck.
Soldier - Win a game with Gideon's deck.
Summoner - Win a game with Kiora's deck.
Vampire - Win a game with Sorin's deck.
You'll Never Get Away With It - Defeat an Archenemy in a game