Late ideas. Elementals are the masters of 'last turn' effects, so I thought I'd try two different supports for them.
Therazane has deserved a spot in Hearthstone for far too long and it seemed fitting to have the final Elemental Lord synergize with Elementals. The effect is based on Grand Magus Antonidas' ability to recall cards from the past few turns and seemed like a logical progression for an Elemental effect.
Marsh Dredger is a callback to Ashes of Outland when Shaman had a 'spell last turn' theme while still providing some support for Elementals. 

My ideas for this week. Unsure why I got hit with a weapon kick, but oh well.

Grand Apothecary Putress is meant as support for a different kind of Weapon/Poison Rogue, where instead of going all in on a single weapon, the Rogue is rewarded for equipping many weapons over the course of a game. The hero power becomes much stronger over the course of the game, but I'd like to see more emphasis on gradual value for Rogue instead of extreme and swingy bursts.

Lord Blackhand by contrast rewards large investment into fewer, but bigger weapons. There have been similar effects, such as with Hoard Pillager, but not needing the weapon to be destroyed enables some extra shenanigans with Remornia, Living Blade. I'm considering changing the effect to making your hero attack after equipping the weapon to better synergize with most of Warrior's weapons.

I'll get feedback in sometime tomorrow :)

Two major themes that stick out from the current Death Knight cards is self damage (Weapons like Frostmourne and spells like Obliterate) and deck destruction (cards like Army of the Dead and Doom Pact), so I tried making legendaries around those ideas. An initiate set legendary would also have to be pretty basic, so I tried to keep the ideas simple.

Painsmith Raznal offers very powerful stabilization potential against enemy boards, but requires they have minions and you have ways to self-damage. It's a powerful and potentially frustrating effect, so stats and cost might be adjusted.

My take on Lord Marrowgar attempts to capture his iconic Bone Storm ability while synergizing with a package that involves removing cards from your deck. 

Elemental Mage has been supported in the past, but never really took off, and Big Hand Mage was only ever supported in Boomsday. Malicious Magmacaster provides mostly new support for Big Hand Mage, but also synergizes with existing Elemental Mage themes of creating lots of cards in hand. Archimonde is a desperate attempt to give Warlocks some real Fel payoff. 0-cost spells can get spooky, but the selection of Warlock's Fel spells isn't that impressive.

Shrewd Broker is an attempt to help the desperately lacking Relic Demon Hunter by providing the ability to draw a Relic on curve, but also to boost them up prior to actually playing one, since Relics are a bit underwhelming without one or two upgrades. The flavor idea is that he'll "sell" you a relic, but will sweeten the deal if you throw in some anima.

Conspicuous Conspirator was made primarily because I liked the name and art, but I'm worried it might be a smidge too similar to Sketchy Stranger. I think it could make for some interesting plays prior to being Infused, but that it might be too good after being Infused.

Feedback:

Super duper late feedback seeking:

I like Big Demons and I cannot lie. Archimonde is intended to work with the fact that if the attack target dies before the attack goes through, the attacking minion can attack again. It's a bit of a niche mechanic, but I thought it was flavorful and provides powerful board clear potential. Sargeras adds some potential lethality to token demon hunter, but only if he is played from hand directly. Cheating him out is still very powerful, but you won't get as big of a swing with his blade. The "Also damages all enemies" works like other cleaving effects we've seen, such as Sweeping Strikes or Stonebound Gargon, just damaging everything instead of just adjacent things.

Rafaam is probably worth a slot, even if you're only getting 1/1 Imps back. In his worst case, you're getting a 6/6 and four 1/1s, refilling the board and pressuring the opponent. Everything above the worst case is still quite good for establishing more board presence, becoming very strong if he's infused.

How about this art? Doesn't 100% fit the Nature-y aspect of the Emerald Nightmare, but I think either fits the Nightmare aspect pretty well. Left one needs a bit of cropping too :P

A bit late to the party, but here are a couple of initial ideas:

De Other Side loses some tempo early, but can potentially be a free deathrattle trigger for things like Undying Disciple. I've thought about pushing it to 3 Durability to make it less likely to be a mid-game swing and make it more late-game oriented. Area 52 provides some handy control for Mage decks that need to build up or stall in the early game. 

Feedback: 

A couple initial ideas. I really like the flavor of Bad Romance, but the effect is admittedly on the basic side. Covetous Shade works nicely with all the stat play Priest has been getting recently, like Switcheroo and some of the Castle Nathria stuff. Lots of cool ideas for the comp so far!

A bit late to the party, but here are some initial ideas. Burn Bright is meant as a some much needed Disco-lock support with a new way to control what you discard. It also has a little pun, with 'Burn Bright' when you burn the right-most card in your hand. Magic Candle seeks to bridge the gap between the Big Spell and Elemental archetypes in Mage that were both somewhat present in Kobolds in Catacombs.  

Turned Witch Doctor into a spell based on feedback. I got a bit worried it was too similar to Eureka! (which I completely forgot existed), so I also made Ethereal Shadow Weaver which is more unique in its effect. Ill try to get feedback out at some point, but time constraints are rough, sorry y'all :(

I've been meaning to more actively participate in these, but time irl stuff is rough. Inquisitor harkens back to Demonic Project, but the added ability to control what you transform and semi-control what your opponent transforms can lead to interesting gameplay patterns. Witchdoctor is another semi-support for Big Shaman, like Muckmorpher, but has the potential utility of removing an opponent's minion.

Two initial ideas to support arhcetypes that never really panned out. Not 100% sold on the Bronzescale effect since it sort of anti-synergizes with Murloc battlecries, but its still a neat archetype that barely got explored. Darkmoon Menagerie Warrior saw some experimentation, but never really came to fruition. Stats on Security might be a bit too large atm considering you could reasonably play 2-3 different minion types by turn 4-5, so it might need to be tuned down.

Excited to be back designing cards! These are the two ideas I landed on after far too much deliberation. I really want Shadow-Deathrattle Priest to be pushed, so I'm going to keep making fake cards to fulfill my fantasy. Copying a strong Deathrattle can be powerful, but that often means you put an expensive minion on the top of your deck with limited ways to draw past it. The Naga from Commander's Trident is the same Naga Centaur from Guard the City. I wanted a weapon that was more clearly supported by Lady Ashvane while also potentially giving support for a Big Warrior. It also works for Control Warrior, but contest with other Control weapons can be tight.

Heck yeah! Glad to hear you're having fun :D

Heck yeah! Trying all the new cards and tools each expansion/rotation is definitely one of the most fun parts of Hearthstone (at least for me). Good luck with the deckbuilding :)

At the time of writing this article I wasn't super hopeful, but the theorycraft streams showed some real promise. For them to be a viable win-condition in the right meta. We'll just have to see whether or not the meta becomes too fast for Warlock to be able to run it.

Glad you like them! It's always fun to see how these opinion pieces can spark discussion on upcoming cards.

I won quite a few Solo-Adventure Runs thanks to 0-mana Unstable Evolution generating me a massive board. R.I.P. wacky evolution shenanigans, you will be missed ;-;