Upcoming Changes in Arena in Update 7.1 - Standard Format, Rarity Distribution Changes, and More!

Here are the upcoming changes coming to Arena in Update 7.1. The really big change is changing Arena from Wild to Standard which could allow for more synergy in drafts. Common and Basic cards are going to show up less frequently, while Flamestrike and Abyssal Enforcer specifically will be showing up approximately 50% less in Arena. Spells appearing in your choices will be increased, and Neutral Classic Cards will show up less.

TLDR

• Arena will be changed from Wild to Standard
• Card Rarity distribution will be changed. The number of Common and Basic cards will show up less frequently. Abyssal Enforcer and Flamestrike will show up 50% less often.
• • From Dean Ayala: 68% Common, 20% Rare, 9% Epic, 3% Legendary on 26 of the 30 picks
• Spells will show up more often.
• Neutral Classic Classic Cards will show up less.
• Golden cards will now be usable in Arena.

Fourth Update

Golden cards will also be available for use in the Arena. This news was added to the original Blizzard post about Arena.

• If you have 2x Golden of a card in any rarity but Legendary, all copies will show up as Golden.
• If you have 1x Golden of a card in any rarity but Legendary, one copy will show up as Golden.
• If you have a Golden copy of a Legendary all copies of that Legendary will show up as Golden.

Third Update

Ben Brode mentions that making Arena Standard could be reverted if it isn't well-received.

Changing Arena to Standard is a big experiment. If players play it for a while and don't enjoy it, we're happy to revert it. We're also likely to experiment with other, crazier formats in the future. Naxx cards only? Only Legendaries and spells?
I think we just need to take a more active role in the Arena experience.
Internally, I don't think we expected much out of the Standard Arena change. But after playtesting, we felt it was pretty fun. I think players will enjoy it, but like I said, try it and let us know.
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Second Update

Dean answered a question about whether or not Team 5 considered making these changes without making Arena Standard.

We did consider it. One of the most difficult draft problems for us to overcome is the ever-increasing card pool. Something I'm relatively sure of is that when a new set comes out, it would be cool to go to arena to draft that new set and check out what its synergies are all about. It becomes difficult to accomplish that when there start to be 1500+ cards available to draft. We want there to be realistic synergies to draft in arena, and we want drafting the set that just came out to be a fun way to discover the latest and greatest new cards.
That said, making arena standard is just one way to do this. I would not consider these current changes to be forever ones. The main takeaway for me in this development time was that smaller card pools lead to more interesting draft experiences, standard-arena specifically was a simple way for us to accomplish that. I could definitely see us rotating older sets in and out of the pool at some point, but for now I'm curious how these current changes will play out. Looking forward to getting feedback once the changes are released.
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Update

Dean Ayala made some additional comments on the Hearthstone Arena Subreddit.

For context, the numbers are around 68% Common, 20% Rare, 9% Epic, 3% Legendary on 26 of the 30 picks. The other 4 picks are 'Rare' picks that have a chance to be upgraded to Epic or Legendary at a slightly higher rate. Flamestrike is 50% less likely to show up refers to it being 50% less likely to show up in terms of cards of its type. For Flamestrike, its definition in terms of the draft tree is ClassCard/Spell/NotMostRecentSet. Meaning cards that share that definition will show up around 50% more often. Abyssal Enforcer is defined as a ClassCard/Minion/MostRecentSet, so it will show up ~50% less than cards in that bucket.
As a further note, rares and commons specifically have a very similar chance to show up on a card by card basis. What I mean by this is Commons as a whole show up more often that Rares, but any individual common will show up about as much as any individual Rare (or close to it). This means you should see a similar amount of Blizzards to Fireballs. This is a little strange so I'm curious what the feedback will be on it.
Talking about the exact chances to get any particular card could be a blog on its own. Each of the classes vary slightly because of the differences in #cards available and minion/spell ratio within each rarity. I recently asked a bunch of friends (who very, very heavily play arena) if they had an idea what the current ratio of commons/rares was and they had no idea. Makes me wonder how necessary a full report on that kind of thing is. In any case, I'm happy to clear up any outstanding questions you all have of the new system. The blog post for this was not the place to go over 100's of numeric details.
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Original Arena update post.

In our next update, we will be making a few changes to the Arena that should make it more interesting for our players and offer a much different experience with each set release.
• Arena will change from Wild format to Standard

• Changes to Card Rarity Distribution

• More Spells in a Run

• Neutral Classic Cards Show Up Less

• A lot of neutral Classic cards tend to be minions without any text that lack interesting effects. While they are great for introducing newer players to Hearthstone and providing baselines for power level comparisons, they don’t make for compelling Arena run choices. This helps make more room for spells, class cards, and expansion cards to show up at a higher rate.

• Golden Cards Show Up In Arena

• If you own golden cards in your collection, copies of that card that appear in your Arena run will show up as golden. If you own a single golden card, the first copy of it you choose will be golden. If you own two copies of a golden card, every copy of that card you choose in the Arena will be golden. If you own one golden Legendary, every copy of that Legendary you choose in Arena will be golden.

These changes will occur in an upcoming update near the end of February. We’ll see you in the Tavern!
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