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
Awaken the Woods 5
I do love this card although I am not sure if it is quite there. As a late game mana dump payoff it is low power and lacking in threat and yet also as early ramp it is also low power, essentially being a 3 mana Llanowar Elf. It is a lot of mana efficiency to sacrifice for the scaling potential. I think X =3 is the sweet spot in my cube where you get to untap and go utterly nuts the turn after. Equally you can just use it before then if it helps curve and be mana efficient. These are also forests which will lend to some good fun synergies I am sure. I'll give this a test but I don't think green has quite enough pay off for a pile of 1/1s to push this enough. This is exactly the sort of card that could become a cube staple if the meta were to shift and things like Sylvan Anthem and Beacon of Creation start popping up in cubes.
Draconic Destiny 3
This is pretty threatening. It reminds me a little of Phoenix of Ash. This needs creatures in play to target while Phoenix needs things in the bin to escape. Both suffer against exile removal although this can come unstuck to well timed instant speed removal of any kind as well. This also needs the dork on the first cast while Phoenix can start life in the bin or cast without any other costs or preconditions from the hand conventionally. This card is a lot of threat against some decks but a massive risk you don't really need to take against others and so that makes it fairly weak overall and not even worth testing for me. Decent power level but presented in an unappealing way.
Persistent Behemoth 2
EDH card. Five mana is too much for this effect and waaay too much for a 2/7. Unearth is basically 2 damage and a land back from the bin. Not terrible but a long way off making up for the front end. The sole use I see for this in my cube antics is a means to get a specific land back from the bin in a deck all about self mill. Green is not short such things either with Life from the Load and Krosan Reclamation but it is nice to have options.
Gruesome Realization 1
Not bad but not great either. There are better tools to do a little bit against opponent's board and better tools to draw with. The former is sufficiently narrow and the latter sufficiently low tempo that I don't see me ever wanting this. Yes, it technically ticks the box of having an always useful mode and a potentially high ceiling situational mode but beyond that aspect this card is failing as modal card that I actually want.
Bladewhip Transmogrant 5
Black does get a lot of these kinds of card. This is very good if it costs just BB to recur and is not at all good when it costs six. This makes the card polar as it will never be good against mono decks, effectively always be good against the three or more colours decks, whilst only sometimes being good in the late game against the two colour decks. That is too much variance for my liking. Especially when I can just pack Scrapheap Scrounger or Skyclave Shade, both of which are broadly better. The main thing of interest on Bladewhip is that it is a zombie which could help turn on Gravecrawler. This is an OK card you might run to give some solid redundancy to a theme but as a stand alone isn't quite there.
Evangel of Synthesis 5
This is too much of a support card to be worth considering and this is just because it is gold. At either 1U or 1B this would be pretty assured of a cube space. Good power and nicely rounded card but very much the wrong sort of gold card. If your Dimir heavily supports a theme that wants looting effects then this is your boy but if not I would steer clear of this kind of card.
Wasteful Harvest 1
Powerful support card but at three mana this has almost no chance of getting used. This is big Impulse, it is Regrowth, it fills the yard full of juice, and it is a nice convenient instant speed. There is a lot going on here but it is just second fiddle to Grapple with the Past or Grisly Salvage or indeed many other two mana cards.
Gnawing Vermin 6
Shambling Ghast meshed with a dash of Stitcher's Supplier! This little rat is a lot of card and a good support tool. It is a pain to attack into while helping setup the sorts of yard based things black likes to get up to. It is a bit low power and narrow. I am likely only playing this in a deck where I have both sac outlets and a desire to fill up the bin, which to be fair is most of the black based weenie decks I make. This has a reasonable hope in cube but it will never be powerful, just an appropriate support and filler, a bit like Voldaren Epicure. It is also the sort of card that rides upon the tide of the meta, if the things it supports fall out of vogue then this goes with them. I see this more as cube glue than I do as an actual cube card. In footballing terms this is not the big name goal scorer, nor is it even the reliable defender, it is more a member of the coaching staff that only die hard fans will even know the name of or recognize!
Goblin Blast-Runner 4
This stupid card could easily be modern playable. It isn't that hard to sac something every turn if most of your lands are sac lands or Horizon lands. A one mana 3/2 menace is insane, it is Delver of Secret levels of good and more consistent in modern. In other formats their consistency might start to compare more but even so, that is an impressive old place for a simple little common. In cube this isn't on enough of the time to be good but there are builds I might slap it in. I am sure it just that this is common that people are not so hyped about it. It is a scary little thing!
Transmogrant Altar 1
When are you getting the time to set this sort of silliness up? You need to sac two 0 mana dorks with this to be up in mana, after four mana upfront investment. This is not even really something I can see in combo or constructed situations either.
Levitating Statue 2
This is very cute, a kind of Sprite Dragon vehicle you "crew" with two mana. In many ways this makes this more dangerous than Sprite as it is hard to kill and can grow pretty massive unhindered. On the other hand however this is very poor in tempo and is only worth turning on once it is grown somewhat. Essentially this is a poor tempo card you want to play in a tempo deck. The upside of safety is not making up for the high cost to actually use this.
Arm's Race 1
A kind of Sneak Attack for artifacts, except it is 4 to use not 1, and so 8 mana for our first "cheat". This will be hard and slow to abuse and is a non-starter if not heavily built around. All in all not looking too good for this card.
Fateful Cooperation 1
Some cute things you can do with this but it is too much phaff and setup to be worth it.
Autonomous Assembler 5
This is super vanilla and not something I would describe as all that powerful but it does seem to tick a lot of the right boxes. Oddly the card this compares closest to for me is Hangarback Walker. Both are scaling dorks that you can power up while in play are well but that are not exactly mana efficient investments. This is a meatier faster acting threat that is restricted to white and doesn't have any on death security or payoff. Really this just feels like a bad Luminarch Aspirant. The card is playable and suitable but it isn't exciting or noteworthy in power. I think most cubes will either ignore this or cut it fairly quickly.