https://www.gamespot.com/articles/free-new-hearthstone-hero-available-during-hallowe/1100-6454072/

A new Hearthstone hero is joining the fray this Halloween season, and you can claim her for free starting October 17. Warlock Nemsy Necrofizzle will be available at any Fireside Gathering Tavern--even after the Hallow's End festivities come to a close.

If you're wondering where you've seen this tiny, red-headed warlock before, you wouldn't be wrong in recognizing her. Nemzy has been seen on the Bog Creeper card from the Whispers of the Old Gods expansion set.