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
Samwise Gamgee 7.5
This is not only a good source of food generation but also a reasonable value tool. Gaining 3 life per creature you play isn't trivial and recurring historic cards is going to own late games. This is too cheap and too rounded, with more than enough power to back it up to not perform well in cube. Absolutely good on its own, it will be devastating with other food cards and is probably good enough to pull some food generators back into the fold. This does useful stuff fairly quickly and backbreaking stuff if left too long unchecked. Two drops that demand answers are good, those that give residual value are good, this looks like it should consistently be both of those things.
Aragorn, the Uniter 7
A kind of Omnath of a card. You lose the EtB card draw but gain stats and potency in the ongoing abilities. Aragorn is a lot easier to trigger than Omnath and should be good for multiple triggers each turn. He gets real silly with gold cards. Play a couple of gold cards in the same turn and things get a little wild! The red and green abilities seem the best with their high impact, power, and reach. They are just going to end games in nice short order. While Aragorn seems good he is vulnerable to removal. Even with multiple triggers on the turn you make him he probably isn't that exciting if then answered. You are going to have wished you played a Muldrifter or something instead! Aragorn has to stay in play a little bit to recuperate the high cost of playing him. Unless you instantly kill your opponent with a chain of red and green cheap spells. Some kind of six mana Aragorn into Manamorphose and Atarka's Command or just a burn spell. That is a lot of pump and face damage to close out a game with. Aragorn is certainly very powerful but he isn't great on curve, you want to hold off and play him with other things, ideally things than can keep him in play a little longer. Less ease of use than Omnath but more interesting to build and play with. A higher ceiling but lower floor and most importantly, a lower average power level than Omnath. He has enough power for cube but he is unwieldy being so gold. I can see a world where the power of Omnath and the pull it has on people to go four or more colours making Aragorn quite a played card. In a world without Omnath I am not sure Aragorn has the pull needed to get play.
Gimli, Mournful Avenger 2
These abilities seem awful. I am never usefully getting indestructible with this. If two guys died combat has happened or I got Wrathed, all too late to be useful. Equally, when are 3 dudes dying to get this rather winning fight? You need to be a sac deck for this and even then fuelling it wouldn't be sustainable. The only good thing here is the steady growing. Sadly on the 3/2 for three starting statline and no keyword combat abilities to scale with growth Gimli seems all round weak.
Gandalf the White 7
Just a 4/5 flash dork for five is surprisingly good in cube. It is terrifying attacking into white decks these days with four or more mana open. More cards like that are generally quite welcome and quite effective. While just average costed stats and flash are not going to make a cube by themselves the various other aspects of Gandalf, while narrow, are quite the extra push. Flash to other stuff is great and a Panharmonicon on those will occasionally be massive. This should always be fine and should sometimes be great. Flavour wise I am looking forward to going on a doubled up Meathook Massacre courtesy of Gandalf.
Sauron, the Dark Lord 5
Yikes, that is quite the ward! Interesting and unique by itself and enough to make me want to test it. While a big boy the total lack of combat abilities does rather make this a slow card. You want it to sit in play generating you tempt and amass value. Not ideal for a six drop. This is powerful but the wrong sort, that combined with being heavily gold should ruin this guys chances. That being said, he is a lot of fun and very different and so I am sure he will get enough novelty play to begin with to keep him covered.
Witch-king of Angmar 7
This is rather savage. It is going to shut down a lot of attacks. You either need exile removal, bounce, or a massive swarm of dorks able to bumrush down in few attacks incurring only relatively minor losses. This card is both quite threatening and well able to defend. Remarkably it doesn't cost you life in anyway adding to the nice defensive aspect. Powerful though this be it is a lame kind of power, like Wurmcoil Engine. It will shut down some archetypes pretty hard while being a really risky play against others. I do not love the polarity of the card but it seems powerful enough and suitable for the cube. Indestructible as a protective mechanism inherently punishes the colours differently. Blue cares not, white cares little, black cares a bit, red cares a lot, and green cries itself to sleep. While not as polarizing as protection from colour dorks those that have or gain indestructible are somewhat along the same lines. Absolutely would prefer this to have some kind of ward instead but regardless of the polarity, the card seems very playable.
Nasty End 2
Nice card but two narrow to justify that extra mana cost on Village Rites. Stuff you aim at your own dorks always wants to be as cheap as possible.
Fangorn, Tree Shepherd 1
Lovely top down design. This feels like Treebeard. Sadly I have no use for this in cube and I don't even see a tribal deck being viable any time soon, and even if it were it is unlikely you would run this in it! Great for EDH though, I can fully see the temptation to make the tribal treefolk deck there, it would be a thing of absolute beauty. Imagine dropping down a Beta Ironroot Treefolk and have it be more than a 3/5. It would feel so good. So right.
Saruman of Many Colours 1
The ward I like. The rest is all a bunch of wordy tedium. It is a get some potential value when you cast your second spell card. You are getting cards and mana when you trigger Saurman and you are also getting things from your opponent which is always a perk. However, a six mana, three colour, 5/4 with no combat perks, all leaves me super cold. Compare this to Bolas's Citadel and it looks shocking. To be honest Future Sight seems significantly better too. This is just an EDH multiplayer card.
Mirkwood Bats 1
Interesting effect but on a 4 mana 2/3 it is not close to the mark on power level.
Voracious Fell-Beast 1
This is decent but sadly Edict effects scale the wrong way with cost. Too often this will hit a dud and be a shocker of a card. Just play Noxious Gearhulk or the many cards like that and not this.
Galadreil, Gift-Giver 2
This just doesn't seem powerful enough. Good utility and good synergy but all a bit slow and vulnerable for a five drop.
Storm of Saruman 4
Love this and love the ward. Just a bit of a way to make it more playable and less punishing. It is still a card you have to survive to and beyond casting which is the hard part, no need then being something you just randomly lose with when they have some Loran or whatever to get it. The ward doesn't even really stop them killing it, it just stops them from doing so with so much tempo gain that it is unrecoverable. So, hardon about ward on big mana things that don't affect the board. just about covered. On to the actual card and what it does... Is forking the 2nd thing each turn good? Very. Can I make it work well in cube? Perhaps. Double stuff is very powerful but you do need to fuel it. Surviving to make a six drop blank, doing so, and then still having stuff is a fairly tall order. It isn't even assured game winning. This is fun but it is not for cube. Six drops there need immediate impact, especially in blue.
Long List of the Ents 7
This is just the loveliest card. I love the flavour, the effect, the gentle break from saga norms. It is just spot on. It is also interesting and powerful. You really do not need to hit every stage for this to be worth it. Three stages is good. Great if they are earlier ones or if they have some scaling potential with where they land. I can see a world where this is just a source or lore counters on a permanent, perhaps reminiscent of Surge Node. This is too unique of a card to not wind up getting some cool action somewhere. I think it is good enough for cube in terms of power but I fear it falls into the camp of neither threat nor answer. Decks can only really pack a few of those and the competition for said slots is pretty heavy. I think this played on turn one or two in a green based muscle deck would be pretty easy to hit four times in cube, would like average over that and manage to get most of them on the earlier turns. That tempo boost might be what keeps the average down with fewer chances of getting to 5 or 6 hits as the game already ended! Sadly, drawn late this looks slow and a bit dodge on getting reliable hits. I think it will just lose out to the likes of protective spells like Blossoming Defence, free spells like Mutagenic Growth, or high impact spells like Ozolith, the Shattered Spire.