Remember how we’ve had Hearthstone (Free) Tavern Brawls where we had a deck full of Webspinners or, more recently, a deck full of portals? This time around, we get to pick one card and get 22 copies of it (plus 8 random cards). As you can imagine, this is going to be quite the crazy one since you can use any card you have, including those not in Standard anymore. Of course you need to keep mana cost in mind because having a deck full of 7-mana cards probably won’t be to your benefit. In these types of Brawl you can go for strong, efficient decks that can quickly win you matches or go all crazy and try every silly idea you’ve ever had.
— Hearthstone (@PlayHearthstone) October 12, 2016
When building that deck, you can either go for a spell or a minion. Fun ideas include bringing a Cruel Taskmaster, Frothing Berkerker, Bloodhoof Brave (if you want to go up to 4 mana and hope to still be alive), going with Discover cards, like Raven Idol, to have more choices and versatility in your deck, or going with spells like Mind Blast to go for constant damage to the face. You can also pick any spell that adds random spells/minions to your hand (like Unstable Portal). You can even go predictable with something like Frostbolt and freeze away. Plenty of fun choices (Prince Malchezaar is always a fine one, too), so go check the Brawl out.