The Gates - Black Dragon Gate, Citadel Gate, Cliffgate, Manor Gate, & Sea Gate:
These cards will be replacing the Thriving lands from Jumpstart as sidegrades.

Blessed Hippogriff, Guardian Naga, & Pegasus Guardian:
These white adventurers all have utility that would have had a spot in the main list of the cube. Added to that, they all have interesting text on their creature side. This gives white drafters really strong opening hands and great top deck opportunities.

Greatsword of Tyr & Goggles of Night:
These coloured artifacts are great! On their own they do not provide defensive stats, but are equipped to do powerful things in the right decks. The greatsword in aggressive decks tyrs through your opponents like an Untethered Express, while the goggles will have your opponents blinded by your card advantage.

Icewind Stalwart:
Restoration Angel at home. Flicker decks will find this to be a reliable addition. The addition of flash would have made this a hot addition.

Sea Hag, Sword Coast Serpent, & Young Blue Dragon:
Blue adventurers

Stunning Strike:
This card is a stunner! Being able to leave mana open means control decks can still have options on what to do on their opponents turn and/or be able to bluff. Once your opponents get blind sided by this the first time, it will be living rent free in their heads. What's cool is this also removes your opponent's creatures from combat so any combat tricks they used will just be wasted.

Hezrou:
This has a nice little trick on the front side, where an opponent is lining up blocks for even trades with your creatures only to have this leap into action. As an added bonus the body comes with flanking for all your creatures.

Nefarious Imp:
This triggers on any permanent leaving the battlefield, making it a bigger upgrade over Warteye Witch which only sees play in sacrifice based decks. This little trickster could be played in flicker decks and even turns your fetch lands into temples.

Stirge:
Another 1/1 flyer for 1 has entered the format, and this one also has some added value. This goes well in aggressive decks. It can chip in for a few bits of damage and be traded away for a new card or used to enable ninjutsu.

Aarakocra Sneak & Vicious Battlerager:
Vicious Battlerager certainly looks like a card that can rumble. With a built in Afflict 5 and an aggressively large booty, this card will almost always guarantee you will reclaim the initiative. Aarakocra Sneak on the other hand has built-in evasion to ensure you can reclaim the initiative.

Arms of Hadar:
Give a round of applause for pauper's first one-sided wrath! This card is certainly reaching out to be one of the best cards from this set.

Fang Dragon & Young Red Dragon:
Red gets two new hot pick ups. They are given another mini-sweeper and an explosive way to ramp. Fang Dragon itself is fragile but it certainly has teeth and can take chunks off your opponent's life. Young Red Dragon can also set up explosive turns for non-green midrange decks and gives red access to evasive threats unlike before.

Carefree Swinemaster & Cloakwood Swarmkeeper:
Carefree Swinemaster has very similar to the effects of Usher of the Fallen, except it has a bigger tail and as its name suggest can swing carefree. This card will be hogging all the lime-light with every attack it makes. Along with it is a 1-drop pay off for token strategies. It requires setup but it can be as powerful as a turn 1 Carrion Feeder in the right deck.

Undercellar Myconid:
This card is interesting bit of tech that can slot in tokens, sacrifice, and ramp strategies. Only time will tell if this addition ages well.

Druidic Ritual:
Unlike Pulse of Murasa and Grapple with the Past, this card lets you take both a creature and a land. Being 1MV more and being only cast at sorcery speed sucks, but the upside is justified.

You Meet in a Tavern:
This is a welcome downshift. While Winding Way and Lead the Stampede are better at digging for creatures, this card gives creature ramp strategies an alternate win-con.

The Guild Gates:
This is a gate themed expansion, and there's no better way to return to an old mechanic then to re-introduce the guild gates. However, even with the return of the gates, the pay-offs weren't strong enough.

Gatecreeper Vine:
With the amount of gates available to us this card will keep finding us the colours we need.

The lost adventurers:

The almost payoffs:
All these cards could be placed in a cube focused on specific archetypes, however even then these cards seem awfully weak payoffs.

The Initiators:
The initiative mechanic has been a lot of fun to play with and you can do some powerful things that it is worth investing in. However these initiators aren't exactly the most powerful and often times you'll have a hard time keeping the initiative.

Value:
These look like good additions for more stream-lined archetype cubes.

Fun splashy cards:
Not much to say about these cards other than they are shiny!

Dicey Cards:
These look like fun but usually the floor is lowered so the ceiling appears higher on these cards.

Almost included:
These were almost included but there are just better options over these cards.