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
Dokuchi Silencer 2
This isn't value nor is it reliable removal. You need abuses for this to start to look good like ways of making it unblockable and things that you want to discard. There are certainly multiple different builds in which I would want to play a card like this but they are all synergy decks. In a draft setting this is never doing enough.
Invigorating Hot Spring 1
Cool take on Fervor but sadly not something you can scale up quite so well. With Fervor, nor cards like it, not exactly being any sort of impressive in cubes this is also not going to do much of much.
Rabbit Battery 6
Cool utility but mostly a Raging Goblin. Haste givers with mana costs have surprisingly low utility in cube. Viewed as a Leonin Scimitar that you can get some free damage and mana efficiency with in the early game makes me like this a bit more. It is less likely to get freely killed by pings being red itself as that means you will face fewer red opponents and will have picked a lot of the things that efficiently answer it yourself! This I feel is worth a test and will perform quite well but not be exciting or powerful enough to last.
Ogre-Head Helm 6
Interesting utility, a Bear to beat with, a Vulshock Morning Star to break stalemates with and be relevant in the midgame, and a cash in mode to draw cards. Much as the latter sounds great needing to connect makes it really suspect. A 2/2 isn't getting through easily and if equipped you are adding lots if conditionality and risk to the card while removing much of the tempo. I suspect this will underperform and is quite possibly just less useful than Rabbit Battery!
Containment Construct 4
Seems like this has loop and thus combo potential. Being a colourless two drop means that combo potential has a chance to be a strong one. This is also fine outside of combo. Just in some kind of madness deck the ability to discard things and effectively draw a card is strong. Pitch my land to a looter, play it from the bin etc. Not a bomb but interesting and useful filler. Too narrow for drafting cubes where it often just going to be an overcost Savannah Lions.
Seismic Wave 7.5
This is quite potent and can be seen as a super Arc Trail or perhaps a spell based Chain-Whirler. This can Bolt one dork and clear out the one toughness things. Sadly for this a number of those are artifacts. Not killing thopter tokens is a shame but it will handle a Lingering Souls very well! Seismic wave is easy to cast, nicely instant, and pleasantly versatile. The power level is variable but typically quite tame however the potential and versatility of the card will likely have it performing well in cube. This will crush decks packing lots of weenies and it will help make non-aggro red strategies better while still being a fine enough inclusion in the aggressive lists.
Dragonspark Reactor 1
A kind of artifact based Shrine of Burning Rage. This is all a bit narrow and slow and needy to get much work done. It might crop up as a combo finisher but I doubt it. I am certainly not playing this anywhere else.
Explosive Singularity 5
A big big big old Stoke the Flames. Not exactly convoke as you cannot reduce the red component of the cost but given the total cost of this one I can't see that being an issue. Ten is a lot of damage in one card and is likely to close a lot of games all by itself. Red is also decent at chucking out tokens. All told this is going to be playable even if it isn't great. You probably wind up getting more mileage out of Inferno Titan or Emissary of Grudges as a top end card. It is not like you are using this as spot removal very often so it is primarily a finisher. Likely just not getting enough play to merit a cube spot but relatively powerful and playable none the less.
Dockside Chef 6
I always get excited about this kind of card and they always underperform. Being a one drop unlike most others of this nature I feel like this has to be good enough but then it could be too narrow. It is a pretty slow card and hard to use as a finisher in aristocrats. It has low impact on the board and is trying to make up for these issues with high utility and synergy. I want this to last but I am not full of hope for it.
Updated Austere Command. Exile added, ability to choose all modes given, graveyard removal added, and yet this still seems too slow and clunky these days. You don't have the option to half Wrath and keep all your small or big dorks while killing off the lions share of the opponents stuff. Mostly though it is just that six mana is a whole lot to get to. You just want a Wrath at four mana and don't care about the other perks. I'll give this a test but I fear cubes are simply too fast and powerful nowadays.
Patchwork Automaton 3
A nice cheap threat that scales up as the game goes on assuming you are playing it in artifact decks. Great with cards like The Ozolith. Quite the poor late game top deck but cheap and powerful enough not to be too worried by such things. Probably making the cut in most aggressive artifact decks although being more of a rank and file card in such a list and not any kind of bomb.
Kami of Transience 2
Powerful but another non-enchantment beater that you want to play in an enchantment deck. It is a support leech rather than a support provider and the bar for those kinds of cards is a whole lot higher. Likely too high for the power level this is offering.
Eiganjo, Seat of the Empire 8
Creature removal on a land, what is not to love? The removal mode is mediocre (at 3 mana) and not all that well suited to aggressive decks but they will all play it regardless as it is a free inclusion so why would you not? Solid card, likely the 2nd best in cycle after the green one, and likely quite close in power to the blue. I can see this being the most commonly reduced in cost with white having a good chunk of cheap and stickier legends to assist with such things.