We've got a round of bugfixes and arena balance changes being added to Hearthstone today in a server-side hotfix. No client downloads will be neccessary.

Quote From GnomeSayin

Patch 29.4.3 is a server-side hotfix patch rolling out now with the following updates and bug fixes.

Arena Updates

The draft card pool has been adjusted, with a handful of card swaps in and out of the card pool for each class and Neutral. Additionally, appearance rates of particular higher-impact cards have been decreased in Shaman, Demon Hunter, and Death Knight and increased in Paladin, Priest, and Warrior.

Bug Fixes and Game Improvements

  • [General] Fixed a bug in the new player experience where some players were unable to skip the Apprentice Track if they hadn’t yet finished the Tavern Guide (players will need to restart their client after skipping for this fix to take effect).
  • [Hearthstone] If Splendiferous Whizbang is Golden, it will now give Golden Hero Portraits and Hero Powers. (Non-Golden Whizbang will still give Golden Hero Portraits and Hero Powers if you have that hero Golden.)
  • [Hearthstone] Fixed a bug with how effects that set stats (like Alarmed Securitybot and Hodir, Father of Giants) worked with Magnetic minions.
  • [Hearthstone] Fixed a bug where The Nighthold sometimes didn’t cast all 3 Secrets.
  • [Battlegrounds] Fixed a bug where Lil’ Rag and Rat Pack were not added to the minion pool as intended.
  • [Battlegrounds] Removed Zilliax pieces from Eudora’s hero power.
  • [Battlegrounds] Fixed a visual bug where Trigore the Lasher’s effect would appear to trigger if you played Backstage Bouncer (dealing damage to your Hero).