This isn't exactly breaking news, but the upcoming Hearthstone expansion, Whispers of the Old Gods, which is... Old God themed... will contain four rather important Legendary minions who you might remember from such raids as Ahn Qiraj and Ulduar (remember, this game is a game within the gameworld of WoW, so it's not like we're saying that Uther or Valeera could actually command an Old God.)
The thing is, while we got to meet C'thun way back in vanilla and Yogg-Saron seven "oh my god I've been playing this game so long" years ago in Wrath, we haven't actually gotten a look close-up at the other two Old Gods, N'zoth (who was probably the puppet-master during Cataclysm, but we only interacted with him indirectly) and Y'Shaarj (who has a good excuse, as he's been dead for eons.) To be fair, those who made it to exalted with the Klaxxi in Mists of Pandaria might have seen a representation of Y'Shaarj in their temple beneath Klaxxi'vess, but for all we know, this could be way off, as even when the first Paragons were being amber'd up, Y'Shaarj might have been long dead.
Nevertheless, Hearthstone has the whole of Warcraft's backstory to provide characters, so they have no problem with reaching into the past and getting a massive eldritch abomination and slapping it on a card.
So far, the only Old God card that has been officially revealed is C'thun. C'thun's whole gimmick will likely require you to build a deck around him/her/it. Several cards are basically C'thun cultists who will buff the Old God even if he's still in your deck or hand (I wonder if it even counts if he's dead or discarded, in case you can rez him.)
Because these C'thun cards would be worthless (or at least underpowered) if you didn't actually have C'thun, they'll be giving him free to anyone who logs in during the "launch event" along with three free packs (don't tell anyone, but I blew a bunch of the pre-order, so I'll be getting significantly more when the expansion launches.)
But the other three have not been revealed yet. Though somehow I feel like Y'shaarj should have a deathrattle that summons all seven Sha (maybe wiping out the rest of your board to make room,) each of which should be tough guys with synergistic abilities.
The thing is, with cards come images of the creatures listed, and that means that we'll actually be getting our first glimpse of N'zoth (and our first good look at Y'Shaarj) through Hearthstone.
While Legion promises to have us at least confront (if not ultimately defeat) one of the biggest threats in Warcraft lore, it seems inevitable that at some point we're going to have to face down N'zoth. Well, now we'll have a picture to send to the police. Keep an eye out for continent-sized fleshy monstrosities.
Possibly looking like this: (SPOILER)