Deck Idea

This deck is basically a combination of 3 different Warlock archetypes: Soul-Control, Galakrond, and BIG--with focus on BIG being supported by Soul-Control and Galakrond. The list focuses on stalling the game until turn 7+ where we can start dropping our huge threats turn after turn... after turn. As such, the list is filled with a bunch of early removal, mid-game taunts, and big, late-game minions.

The inspiration for this deck is the buffed Archwitch Willow--focused on enabling her to be as strong as possible.

General Strategy

Since this list is focused on the mid-late game, we generally are trying to control the board until we can finally start dropping our big threatening minions.

Against Aggro

If you know you are playing against aggro, mulligan for board clears. Against aggro decks that go wide, you will want to keep Dark Skies and School Spirits; against tempo-oriented decks, Unstable Felbolt and Soul Shear work wonders to remove early-game minions.

Devoted Maniac and Shield of Galakrond help to slow down the tempo of the game while also buffing our future Galakrond. If you have already played cards that put Soul Fragments into your deck, then Void Drinker on 5 can completely turn the game in your favor; if not, a 5-mana 4/5 is still ok to stall against aggro for a turn.

Against Combo/Control

If you know you are playing against a slower deck, you will want to hard-mulligan for Invoke cards and Sphere of Sapience. Because we are playing Galakrond, the Wretched, our minions that Invoke Galakrond bring decent stats to the board making them strong tempo plays that generally demand an answer from our opponent.

As for Sphere of Sapience, this weapon actually works very nicely with this list because of Archwitch Willow. This weapon allows us to manipulate our card draws to strengthen how the list performs versus different archetypes. Against aggro, the weapon can shove any non-removal cards to the bottom of our deck to give us a better chance of dealing with the board. Against slower decks, the weapon gives us the ability to choose if we want to add our big demons to our hand or put them back in our deck to make sure Archwitch Willow has demons to pull from our deck. Moreover, because Archwitch Willow doesn't care where the demons are in our deck, putting them at the bottom means we won't have to draw through our entire list to get them back in play.

Synergies

As mentioned earlier, this list is effectively combining 3 different Warlock archetypes; therefore, there are a ton of synergies at work in the list!

IMPS, IMPS EVERYWHERE!

Galakrond, the Wretched allows Warlock to play a strong tempo game by constantly flooding the board with 1/1 IMPS. Galakrond allows us to keep threats on board until we can get to bigger threats in the late-game. In the meantime, we can use the 1/1 demons to heal via Sacrificial Pact and to discount any Jumbo Imps in hand.

On the other hand, if we don't get the chance to draw and discount our Jumbo Imp, it still functions as a big demon for Archwitch Willow to summon from our hand and/or deck. Unfortunately, the big demon pool for Archwitch Willow to pull from is not very exciting, but summoning a 5/5 and two 8/8's for 8-mana isn't that bad.

Healing the Soul

The Soul Fragment package is a solid package for most control Warlock lists in standard, and that holds true for this list. The Soul Fragments provide much needed healing for the list in addition to enabling 3 other cards in the list: a lucky top-deck can provide easy removal in the form of Brittlebone Destroyer both in the mid-game and the late-game; otherwise, these Soul Fragments function as a buff to Void Drinker or a 3/3 with Rush via Soulciologist Malicia.

Animated Demons

Animated Broomstick has demonstrated itself to be a very strong card in decks that summon many minions without removal effects. For example, Dream Portals summoning large dragons that then get Rush for 1 mana has been game-breaking strong for Druid. The purpose of adding Animated Broomstick to this list is to hopefully provide more sustainability in the mid-late game by giving our mid-game taunts Rush or our Archwitch Willow and big demons Rush on turn 9+. Furthermore, Animated Broomstick works well with the 1/1 IMPS summoned from Galakrond and Invokes.

Substitutions

I know this list is rather expensive; fortunately, I have tried out many versions of this list to get to the current form, so I have many recommendations for alternate cards that you can try out (or definitely avoid using) if you are missing cards or want a slightly different feel to the deck! Sphere of Sapience and Soulciologist Malicia are not necessary for the deck to function while still keeping the flavor of the decklist.

Animated Broomstick - If you are missing Sphere of Sapience, Soulciologist Malicia, or any of the non-Soul Fragment removal spells, adding a second Broomstick will work extremely well for the deck. In fact, Animated Broomstick is so good that it is probably better to have 2 of them in the deck anyway ((+1) Animated Broomstick / (-1) Unstable Felbolt)!

Felosophy - This card is actually really fun is this list because it gives the list 2 more large minions to work with in the game. Against aggro, this card usually isn't relevant; however, against value lists, this card can be the difference between getting the win or running out of juice in the late game. If you are patient enough, [Hearthstone Card (Felosohy) Not Found] can give you 4 0-mana 9/9 Jumbo Imps or it can give you a 3rd/4th Void Drinker to fend off aggro or it can give you a 3rd/4th Enhanced Dreadlord for immense board presence. Try this out if you are missing Sphere of Sapience or Soulciologist Malicia.

Siegebreaker - If you are missing Void Drinker or Jumbo Imp, Siegebreaker is a solid substitute in the list. Or, if you just want to be a little greedier on a budget, Siegebreaker works fine in place of Sphere of Sapience or Soulciologist Malicia.

Hellfire/Plague of Flames/Shadow Bolt - If you are missing removal spells in this list, and of the above cards should work as a cheap replacement. Personally, I don't like Plague in this list because it throws away our big minions, but it does work as strong removal with the IMPS. Shadow Bolt is obviously very slow, and Hellfire is dangerous for us since it also damages our face, but both work as budget replacements.

Kanrethad Ebonlocke - Kanrethad Ebonlocke does NOT work in this list very well. Because this list is running Galakrond, Kanrethad Ebonlocke is either going to be an 8-mana 10/9 (after summoning 3 1/1 IMPS), or he will be a 7/6 summoned by Archwitch Willow. If you want to use him, you will need to dismantle the Galakrond package in this list.

Demonic Studies - I definitely do NOT recommend using this card. While tempting at first glance (to cheapen our big demons), the pool of available demons is too inconsistent and will likely cause issues later on in the game with Archwitch Willow.

I had been experimenting with Archwitch Willow prior to the announced buffs, so I was extremely excited to release a list that would actually feel good once the buffs went through. To my surprise, this list does feel good to play, and most opponents don't know what to expect--especially the Jumbo Imps!

There are actually a few different decklists I have experimented with (Dragons, Supreme Archaeology+Plot Twist), but this is the one that feels strongest and most fun to me. If you would like to see versions of those lists, let me know in the comments below!

Good luck and have fun!