0 - unplayable in 40 card singleton
1 - effectively unplayable
2 - has low tier constructed decks it might go in
3 - has mid tier constructed decks it does go in
4 - pretty powerful stuff with several potential homes, able to perform well in lower powered cubes
5 - powerful stuff that is either just too narrow or has too many superior alternatives
6 - fringe cube worthy
7 - cube worthy
8 - cube staple
9 - unpowered cube bomb
10 - powered cube bomb
Ao, the Dawnsky 6
Very powerful but I fear a little to inconsistent in performance for what you want in a top end play. Sometimes it will be an unkillable thing fiving you each turn and totally holding off your attacks and dominating the game which is a nice ceiling. The average is probably going to be like 9 mana and 3 cards worth of stuff for 5 and 1 respectively which is decent enough on a card with OK threat and tempo. It is just that floor you cannot really be risking on a card like this. Catch a Remand, get it flipped by a Teferi, any sort of horror show outcome like that and it is so often the game as a result. There is some potential to try and run Ao with your own Wrath effects so as to be able to hold the board down a bit then rebuild more rapidly. The issue with that is the lower odds on hitting cards to put into play in a deck using Wraths.
Kiari, the Swirling Sky 6
Iymrith is a card that has impressed me greatly in cube which is mostly down to the ward. This alone gives me some hope for Kiara. The ward is a little less here than with Iymrith and the card is a little later in the game where there is more mana spare for paying ward taxes with. Further to that the value Kiara offers is only upon death meaning you really just have a big flier with a smattering of protection which likely isn't enough for this kind of price range.
Life of Toshiro Umezawa // Memory of Toshiro 4
A lot of value here but it is all super slow and a little bit situational for my tastes. If you are killing 1 toughness cards this is nuts, if you are gaining life against burn it is reasonable but if you are not then it is just a slow and low powered dork with none of the desired threat, power, or utility to merit play. High enough power to merit a testing but we are past the time of general high power being enough, now we need power to be in quite specific places.
Michiko's Reign of Truth // Portrait of Michiko 5
Narrow card but incredibly powerful. A kind of side-grade on All that Glitters. This gets a couple of hard hits in with lower risk than an aura and then if that hasn't got the job done it turns into a fairly scary dork. I'll play this in any aggressive enchantment deck or artifact deck. Not being an aura will hurt it relative to All that Glitters in some builds but this still has plenty of game. Low risk and self contained threats with this level of scaling potential go a long way.
Azuza's Many Journeys // Likeness of the Seeker 2
This is a whole lot of card but sadly I am unconvinced this is in any way better than Explore. If I am ramping I do not much card for a 3/3 dork when I could have a card. Yes, this is better tempo, and it is better value, while also offering a more rounded package than Explore. It just isn't things you really want or need combined together all that usefully. This will suck so hard when you play it late in the game or when you have no extra land to play and so it sucks as a cube card despite looking like it is jam packed juice.
The Modern Age // Vector Glider 7
While this is lower power than a number of this cycle that I haven't even bothered to review this has a couple of things going for it. The flying makes the body relevant throughout the game so unlike many of the others the delay does not ruin this. Early card quality is where you want it and yard filling is exceptionally powerful in my cube at present. This is a pretty neat fit into blue tempo decks. It seems to compare pretty favourably to Looter il-Kor as well. The body is more robust, threatening, and relevant while the looting is at least more assured and more rapid. You are getting the more important early couple of loots without getting owned by some ping. Yes, you might not get that 3rd and 4th loot but those are not as important. A good little support card for graveyard and tempo based blue decks. Not for all cubes but with the likes of Etherial Forager, Demilich, Murktide Regent and so forth, this has a hopeful future.
Boseiju, Who Endures 8
This is a very convenient modal card. Essentially a forest with a pile of removal options should you either need such a thing, or simply have more lands than needed. A top tier iteration of the MDFC lands and pretty much an auto include in any green deck. Near zero inclusion cost and quite a lot to be had in return for said inclusion. Not exactly powerful effects but so useful, convenient and free that it is an outstanding card.
Enthusiastic Mechanaut 2
Combo card with ultimately less potential than Electromancer despite seemingly higher power. Artifact decks simply don't love playing high colour intensity cards.
Silver-Fur Master 3
Great ninja lord. Play this in ninja decks to improve them and no where else. Works nicely with a couple of the cute changeling cards that find themselves supporting ninja decks too.
Surgehacker Mech 1
This deals 2 damage for 4 mana then sits around being sad about lack of crew. Can be good but can also be bad which in cube terms these days just means it is bad.
Simian Sling 2.5
Low power but a lot going on for just 1 mana. I can see this winding up supporting a selection of synergy decks as one drop cards with stuff doing on have a habit of doing.
Biting-Palm Ninja 7
As a three drop this is vulnerable to removal but pretty damn scary otherwise. A 3/3 that gets in a free hit and takes your best card is brutal. Ninjutsu makes the connection for hand disruption more likely but makes the card narrower and far lower tempo. Likely this is versatile, disruptive, and threatening enough to make an impact in cube. Concealed Curtain has impressed in cube so far and this has some similarities while packing a better ceiling.
The Reality Chip 2
So either a Steel Wall or a Future Sight you need to equip onto something. Spreading out the cost and having a bit of a speed bump are all nice things to slap on a card draw card but needing a dork feels like it kills this. Quirky but I think not the kind of thing many cubes are looking for.
Jukai Naturalist 2
Perhaps getting into some enchantress decks by virtue of being an enchantment. Not very exciting though.
Secluded Courtyard 4
Another staple for most multicolour tribal decks and a real boost to those with many colours.
Spirited Companion 7
This is the support card white has yearned for. Just a nice clean little dork with draw a card on EtB. You can flicker this, you can equip this, you can attack with it. I am a big fan of it also being an enchantment as it adds an extra layer of support and synergy potential. White can almost draw cards at this point which goes a long way to making it a more appealing colour to play. While an innocuous card I feel like this will have one of the biggest impacts on my cube from this set.
The Wandering Emperor 7
This I love. Flash is the other thing making white more appealing to play with and this is a cool and unique place to find it. This can be quite nasty to run into in combat and can even be a little awkward to run a planeswalker out into. This offers board control, board presence, good defence, a reliable two activations, and it does it all a lot more safely than other walkers. The power isn't extreme here by any means, the loyalty is a little low and the effects are relatively tame but the safety of the card more than makes up for this. I think this is a very exciting control and midrange tool. She is playable in aggressive decks too although she does lose some teeth if you do. The Wandering Emporer is easy to deploy both evading counters or holding them up. She is then pretty easy to establish on the board thus allowing you the best chance to get good value out of.
Tezzeret, Betrayer of the Flesh 3
Some cute potentials with the passive but mostly this is just a fairly generic artifact matters planeswalker than you only really play in artifact decks and then you probably just don't because there are too many other narrow cards like it but better. The power is OK but that is not enough to get it much action in a world where Urza is setting the bar for artifact matters four drops.