If you haven't played it already, this week's Tavern Brawl event in Hearthstone is a neat nod to Blizzard's sister series Diablo.
The special match sees you up against The Dark Wanderer, a new AI-controlled boss. He comes with a deck full of unique secret cards, each of which holds an unusual status effect.
Defeat his minions and they'll leave behind loot in the form of cards - weapons, armor or gold. Defeat these cards during your turn and you'll get a weapon, some armour or a couple of Coin cards to generate extra mana. Nice!
The Dark Wanderer begins each match with three secrets which you'll need to trigger if you want to unlock the round's real secret - an Enigmatic Portal card which transforms your opponent into... The Cow King. Yes, it's a reference to the infamous Diablo 2 Secret Cow Level.
(Players have discovered you can steal the Enigmatic Portal card and yourself become The Cow King).
The original Diablo first released on 31st December 1996, just over 20 years ago.
This is the strongest link yet between another Blizzard property that's not World of Warcraft and Hearthstone itself - one that goes far beyond a simple cardback (although beat the Brawl and you'll get one of those, too).
Hearthstone changed its opening logo at the end of last year - shortening it to Hearthstone from Hearthstone: Heroes of Warcraft. Some speculated this change meant closer links between Blizzard brands were incoming. Ever get that feeling of deja vu?