Thanks to the modular scope of the mechanics in this set I think each color pair offers several strategies. I'm going to focus on the ones each uncommon rewards since... then you actually get rewarded in draft.
Contraband Kingpin - This is a little more subtle, but everything about this card pushes you toward the long game. That means incremental value like Metalspinner’s Puzzleknot and Ovalchase Daredevil. Notice how everything here nets you a card off of playing an artifact. Eventually you just bury your opponent in card advantage.
Empyreal Voyager - So there are several cards in this multicolor cycle that use energy. The key is differentiating how they want to use that energy. This one is about fueling your engines of energy spenders. Feeding a Janjeet Sentry or Riparian Tiger off of this is going to win games.
Engineered Might - The flexibility of this card leads me towards the fabricate mechanic. No matter which side of it you choose to invest in this card rewards your strategy. Cards like Glint-Sleeve Artisan and Peema Outrider will be key here.
Hazardous Conditions - While this looks +1/+1 counter centric, this is really the same strategy BG always falls to. Trading creatures for incremental value and leveraging your resources. Kujar Seedsculptor and Lawless Broker will give you the inevitability you need to grind out your opponents.
Restoration Gearsmith - I'll admit, this one almost seems too generic to sway an archetype. But bringing back a Dhund Operative or Filigree Familiar is going to be a headache for your opponent when these colors have so much efficient removal to negate their value. Fortuitous Find plays a similar role in this deck.
Whirler Virtuoso - This one is doing a lot but I think, ultimately, your goal is to make the thopter in order to gain an evasive flyer and trigger your artifact ETB effects. Being able to spend your energy to make artifacts means Weldfast Wingsmith and Reckless Fireweaver can keep chipping away and keep the tempo on your side.
So what do you think? Do any of these need more elaboration?
I don't think there's enough natural resurrection in the deck to reliably abuse Prized Amalgam. At least not without changing the focus of the deck.
Slip Through Space is an interesting idea. Maybe sideboard? Personally I prefer the inevitability of a tough to remove, evasion granting permanent. For instance, Rogue's Passage serves a similar purpose.
Loam Dryad seems like an easy fit. Anything that fetches a non basic land is probably also something you want to look into in case you don't draw the abbey naturally. Traverse the Ulvenwald, Sylvan Scrying, and Ulvenwald Hydra all seem like reasonable options.
Zombies fit perfectly as all your mill cards are also creatures since you want a critical mass to hit as hard as possible as fast as possible. I believe Forgotten Creation is probably the fastest way to fill your graveyard. All the other creatures are there to put more cards into your graveyard.
Behind the Scenes is more questionable, but it adds more ways to give skulk and simultaneously allows you to use a "go wide" strategy if necessary since Diregraf Colossus also makes tokens.
I did not expect this card to perform so highly, just tossed it in because I had to rely on a few investigate spells for interaction. This card single-handedly carried my very mediocre UG deck to every single victory. Even against a very efficient vampire deck. Seriously, the card advantage this provides is insane. After we saw what it could do the games revolved around this card.
I think the presence of cohort plays into this more than the surge cost. Keep in mind you still have to cast another spell first to trigger surge. Therefore the expected cost goes from U to 2U on average.
I don't like this as an early play/draw smoother. What I do find interesting is that later on you can likely cast whatever you drew since it only costs 1 mana.
I'm not sure how big of an impact this will have but this time you get six normal packs and a seventh seeded pack of seven cards. So you'll never get "stuck" with athe color, just have a few more in one than the others.
I think Charm is safer considering you can easily splash it and it works at virtually any point in the game. Call of the Conclave isn't such a good top deck.
Cloudblazer - As mentioned above, WU rewards flickering and ETB effects. See cards like Acrobatic Maneuver and Aether Tradewinds.
Contraband Kingpin - This is a little more subtle, but everything about this card pushes you toward the long game. That means incremental value like Metalspinner’s Puzzleknot and Ovalchase Daredevil. Notice how everything here nets you a card off of playing an artifact. Eventually you just bury your opponent in card advantage.
Empyreal Voyager - So there are several cards in this multicolor cycle that use energy. The key is differentiating how they want to use that energy. This one is about fueling your engines of energy spenders. Feeding a Janjeet Sentry or Riparian Tiger off of this is going to win games.
Engineered Might - The flexibility of this card leads me towards the fabricate mechanic. No matter which side of it you choose to invest in this card rewards your strategy. Cards like Glint-Sleeve Artisan and Peema Outrider will be key here.
Hazardous Conditions - While this looks +1/+1 counter centric, this is really the same strategy BG always falls to. Trading creatures for incremental value and leveraging your resources. Kujar Seedsculptor and Lawless Broker will give you the inevitability you need to grind out your opponents.
Restoration Gearsmith - I'll admit, this one almost seems too generic to sway an archetype. But bringing back a Dhund Operative or Filigree Familiar is going to be a headache for your opponent when these colors have so much efficient removal to negate their value. Fortuitous Find plays a similar role in this deck.
Unlicensed Disintegration - Play artifacts. I know, what else would you be doing in this set? But take a look at how many cards in BR reward you for doing it. Dhund Operative, Foundry Screecher, Tidy Conclusion, Reckless Fireweaver, Salivating Gremlins, and Welding Sparks just to name the commons!
Veteran Motorist - Obviously play vehicles. Spireside Infiltrator and Renegade Freighter are likely the key commons in this deck.
Voltaic Brawler - Here is where you want all the energy cards. Thriving Rhino and Spontaneous Artist will shine here more than anywhere else.
Whirler Virtuoso - This one is doing a lot but I think, ultimately, your goal is to make the thopter in order to gain an evasive flyer and trigger your artifact ETB effects. Being able to spend your energy to make artifacts means Weldfast Wingsmith and Reckless Fireweaver can keep chipping away and keep the tempo on your side.
So what do you think? Do any of these need more elaboration?
If your opponent has more zombies and you don't possess enough mana you can still cast X=0 to kill a creature
Slip Through Space is an interesting idea. Maybe sideboard? Personally I prefer the inevitability of a tough to remove, evasion granting permanent. For instance, Rogue's Passage serves a similar purpose.
4 Screeching Skaab
4 Diregraf Colossus
2 Mindwrack Demon
3 Forgotten Creation
4 Relentless Dead
4 Fleshbag Marauder
4 Graveblade Marauder
2 Crow of Dark Tidings
1 Behind the Scenes
[Artifacts]
4 Skeleton Key
[Instants]
3 Corpse Churn
3 Compelling Deterrence
[Lands]
4 Sunken Hollow
4 Caves of Koilos
4 Choked Estuary
4 Island
4 Swamp
2 Rogue's Passage
I think focusing solely on Graveblade Marauder is too fragile of a strategy. However, Diregraf Colossus also benefits from a self-mill deck.
Zombies fit perfectly as all your mill cards are also creatures since you want a critical mass to hit as hard as possible as fast as possible. I believe Forgotten Creation is probably the fastest way to fill your graveyard. All the other creatures are there to put more cards into your graveyard.
Behind the Scenes is more questionable, but it adds more ways to give skulk and simultaneously allows you to use a "go wide" strategy if necessary since Diregraf Colossus also makes tokens.
I did not expect this card to perform so highly, just tossed it in because I had to rely on a few investigate spells for interaction. This card single-handedly carried my very mediocre UG deck to every single victory. Even against a very efficient vampire deck. Seriously, the card advantage this provides is insane. After we saw what it could do the games revolved around this card.
Notable contributions were 4 Topan Freeblade, 2 Thunderclap Wyvern, and Whirler Rogue