Rarity is a measure of the quality and scarcity of a card. Cards of higher rarity are typically more powerful or more useful, but are much harder to find and more expensive to craft. Conversely, rarer cards can also be disenchanted into larger amounts of raw materials.
There are 5 rarities: Free, Common, Rare, Epic and Legendary. Each quality has its own color, based on World of Warcraft's gear system, and rarities can generally be recognised by the color of the gem at the bottom center of the card's portrait. The exception is cards from the basic set, which do not feature colored gems. When opening packs, face down cards above common quality will be displayed with an appropriately-colored glow when hovered over.
Free is the lowest level of card rarity, below common, rare, epic and legendary. All free cards belong to the basic set, and therefore do not have any colored gems at the bottom-center of the card's art.
Two of each free card are automatically included in the player's collection.
There are 59 free cards (5 per class and 14 neutral).
Common is the second-lowest level of rarity, above free, but below rare, epic and legendary. Common cards that are not from the basic set can be recognised by a white gem located at the bottom-center of the card's art, and when opening packs do not glow when moused over. Basic common cards do not feature the white gem, but are still marked as common cards. Common cards are found more frequently in packs than cards of any other type of rarity.
Basic common cards that are non-class-specific are automatically included in the player's collection, while all class-specific basic common cards can be obtained by levelling a hero of the appropriate class to level 10. Expert common cards can be obtained from card packs, or through crafting.
There are 186 unique common cards: 94 in the expert set (6 per class and 40 neutral), 74 in the basic set (5 per class and 29 neutral) and 18 in the adventure set (1 per class and 9 neutral).
Rare is the level of rarity above free and common, but below epic and legendary. Rare cards can be recognised by a blue gem located at the bottom-center of the card's art, and when opening packs will display a blue glow when moused over.
There are 85 unique rare cards: 81 in the expert set (5 per class and 36 neutral) and 4 in the adventure set (all neutral).
Epic is the second-highest level of rarity, above free, common and rare, but below legendary. Epic cards can be recognised by a purple gem located at the bottom-center of the card's art, and when opening packs will display a purple glow when hovered over.
Almost all epic cards belong to the expert set, and can be obtained from card packs, or through crafting. Captain's Parrot is the only soulbound epic card. It can be obtained by collecting all Pirate cards from the expert set.
There are 40 unique epic cards: 38 in the expert set (3 per class and 11 neutral) and 2 in the adventure set (both neutral).
Legendary is the highest level of rarity, above free, common, rare and epic. Legendary cards are indicated by an orange gem located at the bottom-center of the card's art, and when opening packs will display an orange glow when moused over. In addition, legendary cards also feature a dragon around the portrait, much like elites and rares in World of Warcraft. Legendary cards are obtained less frequently than cards of any other type of rarity.
Each class currently has a single legendary card specific to their class, with all other legendary cards non-class-specific. Currently, all legendary cards are minion cards.
You may only have one of each legendary in your deck. In addition to being very powerful cards, the characters and items featured in legendary cards are typically very well-known or significant within Warcraft lore. Legendary cards are extremely rare cards and as such very hard to obtain. Playing a legendary card prompts a short piece of unique music.
Almost all legendary cards are part of the expert set, and can be obtained from card packs, or through crafting. A few legendary cards are part of the reward or promotion sets, with their golden and/or regular versions only obtainable through fulfilling specific criteria.
There are 42 legendary cards: 36 in the expert set (1 per class and 27 neutral) and 6 in the adventure set (all neutral).
 In development
- The developers have stated that legendary spells and weapons may be a possibility in the future.
- JR Cook (2014-04-13). Interview with Eric Dodds and Jason Chayes, PAX East 2014.