Here is the full list of all 16 Cards and Castles achievements.
Destroy the enemy castle while the opponent has no units in play.
Collect at least one legendary card!
Craft 10 cards!
Unlock all 5 factions.
Craft one card using shards.
Lose a multiplayer game. It's ok, really!
Win a multiplayer game.
Win 3 or more matches in a single draft.
Deal 10 or more damage in a single attack.
End a turn with at least 6 buildings in play.
Win 10 multiplayer games.
Disenchant a card!
Collect 5 legendary cards.
Win a game with only 1 health left on your castle.
Deal 1000 total damage from attacks.
Craft 50 cards!