So while the meta settles around the changes, it seems a good built to write a guide for. Sadly, Cubelock is a very expensive deck to build, and not easy to play. As a result, it's not a great place to start for new players.
It's built around abusing the combination of Doomguard and Carnivorous Cube. The former is a hard-hitting Charge minion while the latter destroy a friendly minion but later spawns two copies of it.
The idea of the deck is to cheat a Doomguard onto the board, avoiding its discard effect, and Charge with it. Then eat it with the Cube and double up for extra pain.
There are a lot of core cards to the deck, including several Epic and Legendary cards. If you want to build it, you'll either need to have been super lucky opening packs or have a lot of Dust to play with. The essential engine consists of:
- 2 x Dark Pact
- 2 x Kobold Librarian
- 2 x Mortal Coil
- 2 x Defile
- 2 x Hellfire
- 2 x Lesser Amethyst Spellstone
- 2 x Doomguard
- 2 x Possessed Lackey
- 1 x Skull of the Man'ari
- 2 x Voidlord
- 1 x Lord Godfrey
- 1 x Bloodreaver Gul'dan
- 1 x Doomsayer
- 2 x Tar Creeper
- 1 x Voodoo Doll
- 1 x Spiritsinger Umbra
- 2 x Carnivorous Cube
- 2 x Mountain Giant
Most of the expensive cards in this deck are pretty critical. Two you can do without are Spiritsinger Umbra and Lord Godfrey, although the deck will work better if you keep them. The two Giants are perhaps the least critical components of all.
A top substitution is probably a Spellbreaker, as it's very useful for silencing Cubes and Voidlords in the mirror matchup. Acidic Swamp Ooze and Kobold Geomancer are also possibilities.
Faceless Manipulator is also super-useful in the deck, although it's hardly a "budget" suggestion.
Other cards that can work well include Twisting Nether and Siphon Soul, although these are strictly worse than the previous suggestions.
Because the deck thrives on the combo of Doomguard and Carnivorous Cube, it's tempting to keep them in the initial draw.
This tends to be a bad idea. Your card draw power will pull the combo pieces eventually. The idea in the early game is just to stay alive until you do.
The big keepers you want are Kobold Librarian and Possessed Lackey. The former gives you an early body and a card draw. The latter lets you cheat out a big demon the turn after it's played for a big tempo swing.
Other cards to look out for are Mortal Coil, Defile, and the Spellstone. All of these will help keep you safe and your health topped up while you build your hand.
Also consider keeping a Giant unless you're certain you're facing an aggro deck. You'll often draw a big hand, letting you play the fat 8/8 for a minimal cost. And if you've got one or two early minions to play, Hellfire can also be a useful keeper.
We've already discussed the basic principle of the deck, but that's only half the story. This deck needs cards, so the Doomguard's discard effect can be ruinous.
Better to get one on the board indirectly via Skull of the Man'ari or Possessed Lackey. In a pinch though, don't be afraid to risk a direct play if you need to. Better to lose two cards than the game.
If you've used the Skull or the Lackey, the Doomguard will come out at the start of a turn, leaving you a full pool of mana. So, Charge your Doomguard at a likely target, making sure it stays alive.
Then play the Cube to eat it. Congratulations, you've just created the nearest thing Hearthstone has to a time bomb.
For extra terror, you can copy the full Cube with a Faceless Manipulator, if you have one. The trick here is that you get an accurate copy of the Cube with its awful payload. So two full cubes will then unleash four Doomguards, capable of 20 burst damage.
If that's not enough to win outright and your opponent can kill them, there's a second win condition with Bloodreaver Gul'dan.
He resummons some or all of them, for yet another crushing blow. If you're holding this card and hoping to win with it, be careful of putting Voidlords on the board.
If their Deathrattle triggers, the pool of demons Gul'dan randomly summons from will be diluted with weak Voidwalkers.
There's flexibility here, too. Don't get fixated on the combo - sometimes, making a copy of a Giant or a Voidlord can swing the game just as hard.
You can also copy your opponent's minions, and Cube the copies if you want. This can set up some great plays like copying an Obsidian Statue, then Cubing it, which triggers its Deathrattle, taking out your opponent's statue.
All you need to do, then, is to stay alive while you pack your hand with the raw material for this horrible combo. Do so by frequent use of your hero power.
The Spellstone will keep your health topped up. Later, Dark Pact will give you more healing, while also providing a useful trigger for a Lackey or stocked Cube.
In fact, killing your own minions can often been a boon. Feel free to unleash cards like Hellfire and Defile for maximum carnage. If they destroy a Cube or Lackey along with opposing minions, so much the better.
On occasion it can even be worth using Mortal Coil on your own minions to get their Deathrattle effect and a card draw into the bargain. Remember to attack with any minion you're about to self-sacrifice before you do so.
The big thing to watch is your health total. Voidlords are not complete proof against aggro decks, as a single Silence effect renders one useless.
And direct damage can become critical if your health ticks too low. If it starts to look shaky, prioritise deploying defensive or healing cards until the danger has passed.
And avoid using your hero power unless you need it as a route to draw the defence or board clear that you need.