Patch 20.4.0.84593

 is a Hearthstone patch released June 3, 2021. It is a large patch, adding all the data for Wailing Caverns as well as changes to Battlegrounds, a new Arena rotation, data for Book of Heroes and Book of Mercenaries, and a new purchasing system for card backs and alternate heroes.

Patch Notes
The 20.4 patch, which will release on June 3, includes the Wailing Caverns Mini-Set, updates across several modes, returning Card Backs and Hero Skins, and improvements throughout the game.

Wailing Caverns Mini-Set
The new Mini-Set is here!

The Wailing Caverns Mini-Set, launching worldwide on June 3, consists of 35 distinct cards—which can all be obtained from Forged in the Barrens card packs! The entire 66-card set (4 Legendary cards, 1 Epic card (x2), 14 Rare cards (x2), and 16 Common cards (x2)) is also available for purchase from the in-game or web shop, for either $14.99 or 2000 Gold!

Standard Updates

 * First Day of School
 * Old: Add 3 random 1-Cost minions to your hand. → New: Add 2 random 1-Cost minions to your hand.


 * Hand of A'dal
 * Old: Give a minion +2/+2. Draw a card. → New: Give a minion +2/+1. Draw a card.

The cards listed above will be eligible for a full dust refund for 2 weeks after the 20.4 patch goes live.


 * ''Dev Comment: As we move into the launch of the Wailing Caverns Mini-Set, we’re taking the opportunity to hit some of Paladin’s generic power. First Day of School and Hand of A’dal are strong performers played in all four main Paladin archetypes (Libram, Aggro, Secret, and Menagerie), and we are nerfing them in 20.4 to help other classes close the gap with Paladin. Another note on First Day of School: While the last balance change for this card only resulted in a mild change in power, we will still be attempting changes like it in the future. Our current balance philosophy is to move forward with light changes when we can, as we did when we first repositioned First Day of School, and we’ve seen great results over the past year with this approach. It’s important to us that players’ decks usually stay intact following balance changes, even if the power of the deck may shift down. This approach then leaves us open to make further adjustments later if we need to, like we have here.


 * Unbound Elemental
 * Old: Whenever you play a card with Overload, gain +1/+1. → New: After you play a card with Overload, gain +1/+1.

Battlegrounds Updates

 * NEW HEROES


 * Mutanus the Devourer
 * Devour [Costs 0]
 * Remove a friendly minion. Spit its stats onto another. Gain 1 Gold.


 * Guff Runetotem
 * Natural Balance [Costs 1]
 * Give a friendly minion of each Tavern Tier +2/+1.


 * ''Players with Battlegrounds Perks will have early access to the new Heroes above before they are formally released on June 17.


 * HERO POOL UPDATE


 * Maiev Shadowsong has been temporarily removed from the Battlegrounds Hero Pool.


 * NEW MINION


 * Hexruin Marauder
 * [Tier 4, Demon] 3 Attack, 5 Health. At the end of your turn, if you have 6 or fewer minions, gain +3/+3.


 * MINION POOL UPDATES


 * Quilboar are no longer guaranteed to be in every Battlegrounds match.
 * Siegebreaker has been removed from Battlegrounds.
 * Cap'n Hoggarr’s text has been reworded to say “whenever” instead of “after” (no functional change).

Duels Updates
When the 20.4 patch launches on June 3, the Wailing Caverns Mini-Set will be added to loot buckets and the pool of eligible cards you can use to build your 15-card starter deck. The patch also includes updates to the passive treasures system to make the system less deterministic.

Arena Rotation
When the 20.4 patch launches on June 3, the Arena will include cards from the following sets:


 * Wailing Caverns Mini-Set
 * Forged in the Barrens
 * Darkmoon Races Mini-Set
 * Madness at the Darkmoon Faire
 * Scholomance Academy
 * Ashes of Outland
 * Kobolds & Catacombs
 * Goblins vs. Gnomes
 * Core

More Returning Card Backs & Hero Skins Than Ever Before!
A ton of skins and card backs from the past are returning to the shop and will be purchasable with Gold!

We’re excited to share that many previously released Card Backs and Hero Skins will become available for purchase with Gold as of the 20.4 patch! With this patch, 94 Card Backs and 11 Hero Skins will be available! The following Hero Skins will be available at launch:


 * Magni Bronzebeard*
 * Alleria Windrunner*
 * Medivh*
 * Khadgar*
 * Sylvanas Windrunner*
 * Lei Shen/Thunder King*
 * Dame Hazelbark*
 * Maiev Shadowsong
 * Morgl the Oracle
 * Lunara
 * Sir Annoy-O

* These Hero Skins also include their associated Card Back.

Card Backs will be available for either 500 or 600 Gold, while Hero Skins will be available for either 1200 or 1800 Gold. Simply navigate to the item you want within your Collection and click on it to purchase it with Gold. New Card Backs and Hero Skins will continue to appear in the shop when first introduced, but we will periodically update the Collection with more returning Card Backs and Hero Skins going forward.

Find the item you want in your collection, click on it, and hit buy with Gold!

Book of Mercenaries Xyrella – Live with 20.4 Patch
The Draenei called it The Night of Falling Stars, when shards of fractured Light rained across Azeroth. Guided by a mysterious voice, the priest Xyrella now searches the Barrens for the glowing shards which the voice promises can save her daughter's life. The priest's quest will be explored in Book of Mercenaries Xyrella, launching June 3rd. Defeating all 8 bosses in this linear adventure will reward 1 Priest pack, containing only Priest cards from Standard!

Book of Mercenaries Guff – Coming June 15
Guff Runetotem has always just wanted to help, but when "helping" means accidentally starting a treant rampage that nearly flattens Thunder Bluff, Guff vows to set things right. His quest for redemption leads him and his companions to the Wailing Caverns. What Guff finds inside will be revealed in Book of Mercenaries Guff, launching June 15th. Defeating all 8 bosses in this linear adventure will reward 1 Druid pack, containing only Druid cards from Standard!

Book of Heroes Malfurion – Coming June 22
As the first druid, Malfurion has solemnly defended the natural world from threats, including his own brother, for thousands of years. Despite his steadfast protection, the perils of Azeroth have only increased with time, and the enemies of the wilds grow in both strength and cruelty. Malfurion’s harrowing tale will be told in Book of Heroes Malfurion, launching June 22nd. Defeating all 8 bosses in this linear adventure will reward 1 Druid pack, containing only Druid cards from Standard!

Bug Fixes & Game Improvements

 * Updated Friends List messaging to indicate whether friends in Play Mode are playing Ranked or Casual, and which format they are playing.
 * Fixed a bug where copying Imprisoned Celestial with Mirror Entity resulted in the copied Imprisoned Celestial being unable to activate its Spellburst effect after awakening.
 * (NEW) Fixed a bug that prevented the “Borrow Decks” feature from working.
 * Fixed a bug where cost-reduction effects on Dormant minions would persist after the Dormant minion was played and awakened.
 * Fixed a bug where effects that trigger after or whenever a spell is cast would not trigger if Oh My Yogg! converted the spell into a new spell with no valid targets.
 * Fixed a bug that caused Sparkjoy Cheat to use both Scabbs Cutterbutter discounts if it put a Secret into play with its effect.
 * Fixed a bug where Guidance's Spirit Path option was not being counted as an Overload card when selected.
 * Fixed a bug where Bogbeam and Ironbark’s cost reduction effects would not activate after casting Celestial Alignment and going back up to at least 7 Mana Crystals.
 * Fixed a bug where Crabrider was not recognized as a Battlecry minion by cards like Field Contact.
 * Updated the wording of Shield Slam so that it accurately represents the way that the card interacts with Spell Damage bonuses.
 * Added language clarifying that both Classic and non-Classic versions of a card are removed from your collection when either version is disenchanted.
 * Fixed a bug where Elite Tauren Chieftain would sometimes generate non-Classic versions of cards when played in Classic.
 * “Quilboars” has been corrected to “Quilboar” as the proper plural form of Quilboar when displaying Battlegrounds minion types.
 * Fixed a bug where Reckless Apprentice’s effect would cause some minion-only Hero Powers to hit the enemy hero.
 * Fixed a bug that would result in duplicate treasures being offered in Duels.
 * Prevented cards of the same name from different sets being offered in the same Arena run.
 * Updated the Player Profile to display total wins for each game mode.
 * Fixed a bug where progress related to progression tracks, such as the “Tavern Regular” achievement, would not properly update.
 * Fixed a bug where reward pop-ups would sometimes not properly appear when the reward was earned.
 * Fixed a bug that prevented players from switching accounts on iOS devices.
 * Updated the New Player Experience to remove certain restrictions and to better indicate locked heroes, modes, and other features.
 * Updated MMR calculation for returning players to better account for their time away from the game.
 * Fixed a bug where effects that added copies of Diamond cards to a player’s hand or deck would add Golden versions instead of Diamond versions.
 * Fixed a bug that would make some Diamond cards not appear in your collection if owned.
 * Fixed a bug that would sometimes cause cards in hand to arbitrarily change positions.
 * Fixed a bug where the wrong description would sometimes appear for items in the in-game shop.