Week five of the 'Hearthstone' Blackrock Mountain Adventure mode is drawing near as gamers are gearing up to get their hands on the final new cards, fight the last bosses, and figure out the latest meta. The fifth and final wing releases this week it's none other than the infamous and treacherous Hidden Laboratory.

Starting off with a little bit of lore, for those familiar and unfamiliar with the origin of the Hidden Lab, Blizzard posted a tidbit of information about it via Battle.Net, "So the stupid, incompetent, and disappointing minions of Blackwing Lair were no match for you after all. Huh. That's"¦ well, that's certainly unexpected. No matter. The awesome experiments of the Hidden Laboratory will stop you cold in your tracks and make you regret ever challenging the TRUE master of Blackrock Mountain!"

Based on the hint about the "TRUE master of Blackrock Mountain" it's clear that players will get the chance to face the one and only Nefarian.

Before revealing the final four bosses slated for release this week, gamers can preview the last cards that they'll be able to splice into their decks or construct new decks around below:

On a side note, week 5 marks the only week that one Class challenge is released upon completion of the wing. The only class left in the pre-constructed 'Hearthstone' challenge mode is the Paladin.

Moving into the bosses that players are going to face in BRM Wing 5: Hidden Laboratory, first on the list is Omnotron Defense System. For those unfamiliar this boss, it's a "System" so it's actually more than one boss, but they act together as a single unit, alternating actions. Their Hero Powers range in how much Mana they cost, as noted below:

• Activate Arcanotron (2): Activate Arcanotron!

• Activate Toxitron (4): Activate Toxitron!

• Activate Electron (6): Activate Electron!

• Activate Magmatron (8): Activate Magmatron!

• Activate! (4): Activate a random Tron.

Next up to bat is Maloriak who many will know is quite the fitting fight for BRM Hidden Lab as he possesses a strange obsession with potions. His Hero Power is passive and costs no Mana, "The Alchemist (Passive): Whenever a minion is summoned, swap its Attack and Health."

After that, 'Hearthstone' players will face-off against Atramedes who looks like a pretty powerful dragon. His Hero Power costs one Mana, it reads, "Echolocate (1): Equip a weapon that grows as your opponent plays cards."

At last the final boss of the Blackrock Mountain Adventure mode expansion follows Atramedes, and once again, he's the "TRUE master of Blackrock Mountain!," and evidently one of the most powerful dragons in Warcraft history.

This time around, Nefarian has two Hero Powers, "Bone Minions (2): Summon two 2/1 Bone Constructs," and "Nefarian Strikes! (0): Nefarian rains fire from above!"

Upon completion of the final BRM wing 5 boss, players will earn the final Legendary card for the latest 'Hearthstone' expansion, Nefarian himself.

Beyond all that, what 'Hearthstone' players are really looking to find out, is on what day and at what time the Hidden Laboratory will be unlocked. While there is no official date and time, following the trends of the previous wing releases reveals a distinct pattern.

In the US, the next wing will most likely launch on Thursday, April 30 at approximately 10:00 AM PDT or 1:00 PM EST. In the EU however, the new wing will probably not be available until roughly 19:00 CEST.

Once again, there is no official word as to when the new wing will be available, however, a pattern has held true since the release of the first set of new cards and bosses.

To check out the official Blackrock Mountain Adventure: Hidden Laboratory wing in detail, head to the official Blizzard post on Battle.net.