Patch 8.4.0.20022

 is a Hearthstone patch released July 10th, 2017. It is a medium sized patch that includes the nerf to The Caverns Below and the inclusion of the Knights of the Frozen Throne preorder.

Knights of the Frozen Throne

 * Pre-purchase for Knights of the Frozen Throne, Hearthstone’s latest expansion, is now available from both the in-game Shop and online! You can pre-purchase 50 card packs and get the Frostmourne card back for $49.99 USD.
 * Pre-purchased card packs and the Frostmourne card back will now appear in-game. Knights of the Frozen Throne card packs can be opened when the expansion is released in August.

Balance Update

 * The Caverns Below now reads: Quest: Play five minions with the same name. Reward: Crystal Core.
 * The Caverns Below is uniquely powerful versus several slower, control-oriented decks and is played often enough to push those decks out of play. While deck diversity in Ranked Play is good, a change to The Caverns Below was still warranted to help keep that trend going into the future.
 * The Caverns Below can now be disenchanted for full Arcane Dust value until July 24 PDT.

Arena Balance
Jungle Giants, The Marsh Queen, Open the Waygate, The Last Kaleidosaur, Awaken the Makers, The Caverns Below, Unite the Murlocs, Lakkari Sacrifice, Fire Plume's Heart, Klaxxi Amber-Weaver, Dark Arakkoa, Cult Sorcerer, Hooded Acolyte, Twilight Darkmender, Blade of C'Thun, Usher of Souls, Ancient Shieldbearer, Twilight Geomancer, Disciple of C'Thun, Twilight Elder, C'Thun's Chosen, Crazed Worshipper, Skeram Cultist, Twin Emperor Vek'lor, Doomcaller, C'Thun, Dust Devil, Totemic Might, Ancestral Healing, Windspeaker, Sacrificial Pact, Sense Demons, Void Crusher, Succubus, Savagery, Soul of the Forest, Mark of Nature, Warsong Commander, Rampage, Starving Buzzard, Timber Wolf, Snipe, Mind Blast, Lightwell, Purify and Inner Fire.
 * Note: Neutral cards form the basis for draft appearance rates.
 * On average, Arena runs consist of 60% Common, 28% Rare, 10% Epic, and about 2% Legendary cards.
 * Class minions are +100% more common than neutral cards.
 * Class Spells and Weapons are +175% more common than neutral cards.
 * Journey to Un'Goro cards receive an additional +50% increase in their appearance rate.
 * The following cards are unavailable in arena:
 * Flamestrike, Vicious Fledgling, and Abyssal Enforcer, and will appear in drafts 50% less often.
 * This change was in fact already in effect for Flamestrike and Abyssal Enforcer as of Patch 7.1.0.17720.
 * Popular cards had small drop rate changes to address class balance concerns. (Note - These changes range from 1-5%. They are small enough that they are unlikely to be noticed during an individual draft, but should have enough cumulative impact to help improve class balance.)
 * We’re working to improve the Arena experience, and your feedback is always appreciated!

Other Changes

 * The following minions are now Elementals:
 * Jade Spirit
 * Djinni of Zephyrs
 * Flame of Azzinoth
 * Mana Geode
 * Crystal
 * Hallazeal the Ascended


 * Added the following card backs:
 * Frostmourne – Acquired from the Knights of the Frozen Throne pre-purchase bundle.
 * HearthS’mores – Acquired from achieving Rank 20 in Ranked Play, July 2017.

Bug fixes

 * Fixed an issue that could cause Hearthstone to freeze when closing.
 * Fixed some visual issues associated with Deck Importing.