Blizzard Entertainment's latest addition to its popular online card game 'Hearthstone' is coming to a close as there are only two wings left to release in the Blackrock Mountain Adventure. This week, gamers can expect to unlock Wing 4: Blackwing Lair and its new cards and boss fights.

With the new wing of the expansion comes new lore for fans and those not familiar with Blackwing Lair. The official Battle.Net post reads, "Say what you will about Nefarian* - that he's insane, sadistic, arrogant, and perhaps a little too enamored with his own brilliance - but you can't accuse him of being a bad host. For those brave enough to enter Blackwing Lair, the dragon brings out only the finest and most eclectic selection of challenges."

On a side note, there's a superscript footnote that reads, "*Just not to his face."

Moving along into some of the cards players will be able to splice and work into their decks, seven of them will be made available upon completion of the Blackrock Mountain Adventure: Blackwing Lair wing. Check out the new cards for week 4 below:

Before listing the bosses 'Hearthstone' players will face this week, the two new class challenges this time around are the Warlock and Rogue class challenges.

One thing that sets this wing apart from some of the others, is that there's four bosses listed as opponents for BRM Blackwing Lair.

First up is Razorgore the Untamed, who some might remember was the first boss in the Blackwing Lair 'World of Warcraft' raid which syncs with the Blackrock Mountain Adventure update. Razorgore known for his room full of eggs has a fitting one Mana hero power, "The Rookery (1): Give all Corrupted Eggs +1 Health, then summon one."

Next is the second boss in WoW's Blackwing Lair, Vaelastrasz the Corrupt, whose hero power "Essence of the Red" costs zero Mana and makes "Each player draws 2 cards."

After that, the boss order takes quite a leap forward as Chromaggus stands in the way of the final boss once more. Chromaggus, also the Legendary card received for beating this wing, has a zero Mana hero power which reads "Brood Affliction (0): At the end of your turn, add a Brood Affliction card to your opponent's hand."

Last but not least, Lord Victor Nefarius will be the next opponent 'Hearthstone' players will have to face in order to receive all seven BRM cards this week. However, his hero power is the most ambiguous of all, as it reads, "True Form (1): Let the games begin!"

Nevertheless, there's a strong chance Nefarious' hero power will allow him to transform into the dragon Nefarian, but that's only speculation at this point.

Beyond all that, and after learning what to expect in week 4 of the BRM Adventure mode, gamers want to know when they'll be able to access the new content. As it stands, there's no official release date for Wing 4, but they all seem to be following a pattern. The next wing is likely to launch on Thursday, April 23.

To check out the full description of the Blackrock Mountain Adventure: Blackwing Lair wing, check out the official Blizzard post on Battle.Net.