I'm mostly retired as far as Cube goes, but I still follow the printing of new cards and play my occasional MTGO Cube draft (or even play Cube in real life, when all the stars align).
I feel discussions here are less heated now that there are so many different powerful choices for Cube managers. It is more and more obvious that there is no 'right' or 'wrong' choice, just different choices that may lead to different results. That said, Absorb would be the wrong choice, obviously.
Mind Twist is the only card from that list that I like playing in an "unpowered" Cube with no fast mana. To me it feels slightly broken without being too broken. Cards like Mind Shatter and Stupor in comparison to Mind Twist and Hymn to Tourach show, how difficult it is to price discard in a competitive, but non-broken way.
I have tried Channel and Mana Drain in an environment with no fast mana, but I did not like how they played. Channel allows broken early game plays, which imo is counter to the whole idea of excluding fast mana. Mana Drain is just absurd now that mana burn no longer is a thing: the worst case scenario is Counterspell, which is a very good Cube card already.
I think Channel, Mana Drain and Time Walk qualify as fast mana. The only reason that I even gave Channel and Mana Drain a shot is the heavier color commitment they seem to require. But the cards are powerful enough and mostly green/mostly blue decks respectively are strong enough even without them, so the color requirements are not enough of a drawback.
I think Release the Gremlins has a big gap in power between powered and unpowered Cubes. In a powered Cube, it will almost always find one or more targets, whereas in an unpowered Cube, it is easily imaginable that you cannot even cast it for lack of a target. Maybe the verdict 540+ for unpowered Cubes is a bit too generous, but I can see it being very good in powered Cubes.
As for Walking Ballista, I think as long as you compare it to Triskelion, you can't do it justice. Removing +1/+1 counters in order to deal damage to target creature or player and the type line really are the only things these two creatures have in common.
Ire Shaman way over Ash Zealot. These days, a permanent has to be flat awesome to justify CC mana costs. I've got a few: Bloodghast and Rofellos. That's it. Anything else isn't worth the hassle of having to run 13 sources or whatever to reliably stick it on T2.
Unless you include CC cards as a design choice. I actually like to encourage decks that are heavily in one color and just splash for a second instead of having most decks being solidly in 2+ colors.
Nice! A mono-blue Voidslime sounds like a reasonable Cube card. For smaller lists, it will probably still not make the cut between all the playable two mana counters and the extremely powerful four mana counters, but I think it should be very welcome for big lists and may be good enough for medium lists as well.
Kargan Dragonlord: At a quick glance your Cube (like mine) does not play fast mana, and I really like it in this context.
Of the three cards you suggest, I'd probably add Lightning Mauler and Hellspark Elemental. I am not a fan of "player burn creatures" in general, but Hellspark does have good synergies (not only with sacrifice outlets but also with looters).
I think Library of Alexandria is even better in an unpowered Cube than in a powered Cube. With Library, you trade some tempo for an additional draw step every turn, which pays of very quickly. The way to beat Library is by being fast, and powered Cubes add some additional tools for decks that are looking for an early kill. I would not recommend playing the card in an unpowered Cube.
The last time I stepped into an actual Library? I can't even remember because books are so cheap nowadays.
I find the best way to learn to appreciate an archetype and to make one interested in learning more about it is getting beaten by it. So just shuffle up and play the Cube!
I see all the tools for fast reanimator. I think Exhume would be quite good in your list, even though you don't have very many big monsters to get back from the graveyard (you don't want too many, so maybe the number is exactly right).
Hivemind comes to mind when I think back on what drove some people away from here. It was really easy to get the impression that there was a "right" way to construct a Cube and many "wrong" ones. Cube was defined as a singleton format with the most powerful cards ever printed. Power rankings and the Cube comparison thread listed the "must-plays" (or, at least, some users seemed to read it that way instead of using those resources as a starting point for their own ideas) and everyone excluding cards of that category was told that they are wrong. It was hard to get an actual discussion going on the merits of certain non-standard ideas.
I am less active in recent years (I have only so much tinkering in me, and these days I spend it mostly on my job and not on my Cube). That said, I get the impression that things have changed and that now it's easier to discuss different ideas. With all the powerful cards printed in recent years, we now have the ability to build Cubes with different cards but similar power level. I think that helped with shifting the discussion from "which card is more powerful" to "which card supports this archetype better".
I like Tolarian Academy. In a Powered Cube, you can get super broken starts, which seems adequate for that format. In an Unpowered Cube without fast mana, it still helps with playing the more expensive artifacts ahead of curve, but without feeling oppressive. It also requires a specific deck in order to be better than an Island (or even as good!).
Demonic Tutor is such a great card in a singleton environment, so many cards that you can get!
A bit late to the Sci Fi movies party, but that is what really made me write this post: Starship Troopers and Pitch Black are two of my favorites and I think they are often undervalued.
I feel that both Erratic Portal and Crystal Shard suffer from the ever increasing tempo in Cube decks, at least for smaller lists. But I agree with wtwlf123, I'd probably add neither or both.
Spoiler season just does not feel complete without your top 20 (P)review. A very valuable resource, thank you very much for taking the time to write this!
Wildest Dreams might be a good card for the more combo-oriented Cubes, I guess?
I prefer talismans, because you are not forced to use mana in chunks of two. I would run talismans where possible.
With enough signets/talismans, it is often almost as easy to splash the fourth or even fifth color as it is to splash the third. I prefer the 4/5-color good-stuff decks to require some effort regarding the mana base rather than it coming together incidentally. Therefore, I prioritize non-signet/talisman mana rocks and fill up with signets/talismans as needed. Coldsteel Heart, Everflowing Chalice, Guardian Idol, Mind Stone and Prismatic Lens are all reasonable choices. Fellwar Stone, Star Compass and Sphere of the Suns are not as good as signets but still have the "problem" of incidental color fixing, so I choose not to run them. Thought Vessel and Fractured Powerstone virtually or actually don't do anything other than tapping for 1; they are options if you want to further reduce the color fixing available on mana rocks.
I'm mostly retired as far as Cube goes, but I still follow the printing of new cards and play my occasional MTGO Cube draft (or even play Cube in real life, when all the stars align).
I feel discussions here are less heated now that there are so many different powerful choices for Cube managers. It is more and more obvious that there is no 'right' or 'wrong' choice, just different choices that may lead to different results. That said, Absorb would be the wrong choice, obviously.
I have tried Channel and Mana Drain in an environment with no fast mana, but I did not like how they played. Channel allows broken early game plays, which imo is counter to the whole idea of excluding fast mana. Mana Drain is just absurd now that mana burn no longer is a thing: the worst case scenario is Counterspell, which is a very good Cube card already.
I think Channel, Mana Drain and Time Walk qualify as fast mana. The only reason that I even gave Channel and Mana Drain a shot is the heavier color commitment they seem to require. But the cards are powerful enough and mostly green/mostly blue decks respectively are strong enough even without them, so the color requirements are not enough of a drawback.
2. Creatures in green are so important, especially because of cards like Natural Order, Green Sun's Zenith, Tooth and Nail but also Worldly Tutor, Survival of the Fittest, Primal Command and Fauna Shaman. I like Birthing Pod a lot and Eldritch Evolution looks fun too, but keep in mind there is only so much room for non-creatures.
3. Gitaxian Probe is a good colorless card imho. It will almost always make the deck and therefore is worth a pick and therefore a slot in the Cube.
4. I don't have any experience with this card, but it looks decent.
5. Redcap is perfectly fine as a black card.
As for Walking Ballista, I think as long as you compare it to Triskelion, you can't do it justice. Removing +1/+1 counters in order to deal damage to target creature or player and the type line really are the only things these two creatures have in common.
Mogg War Marshal is a good token card.
Kargan Dragonlord: At a quick glance your Cube (like mine) does not play fast mana, and I really like it in this context.
Of the three cards you suggest, I'd probably add Lightning Mauler and Hellspark Elemental. I am not a fan of "player burn creatures" in general, but Hellspark does have good synergies (not only with sacrifice outlets but also with looters).
The last time I stepped into an actual Library? I can't even remember because books are so cheap nowadays.
Hivemind comes to mind when I think back on what drove some people away from here. It was really easy to get the impression that there was a "right" way to construct a Cube and many "wrong" ones. Cube was defined as a singleton format with the most powerful cards ever printed. Power rankings and the Cube comparison thread listed the "must-plays" (or, at least, some users seemed to read it that way instead of using those resources as a starting point for their own ideas) and everyone excluding cards of that category was told that they are wrong. It was hard to get an actual discussion going on the merits of certain non-standard ideas.
I am less active in recent years (I have only so much tinkering in me, and these days I spend it mostly on my job and not on my Cube). That said, I get the impression that things have changed and that now it's easier to discuss different ideas. With all the powerful cards printed in recent years, we now have the ability to build Cubes with different cards but similar power level. I think that helped with shifting the discussion from "which card is more powerful" to "which card supports this archetype better".
Demonic Tutor is such a great card in a singleton environment, so many cards that you can get!
A bit late to the Sci Fi movies party, but that is what really made me write this post: Starship Troopers and Pitch Black are two of my favorites and I think they are often undervalued.
Wildest Dreams might be a good card for the more combo-oriented Cubes, I guess?
With enough signets/talismans, it is often almost as easy to splash the fourth or even fifth color as it is to splash the third. I prefer the 4/5-color good-stuff decks to require some effort regarding the mana base rather than it coming together incidentally. Therefore, I prioritize non-signet/talisman mana rocks and fill up with signets/talismans as needed. Coldsteel Heart, Everflowing Chalice, Guardian Idol, Mind Stone and Prismatic Lens are all reasonable choices. Fellwar Stone, Star Compass and Sphere of the Suns are not as good as signets but still have the "problem" of incidental color fixing, so I choose not to run them. Thought Vessel and Fractured Powerstone virtually or actually don't do anything other than tapping for 1; they are options if you want to further reduce the color fixing available on mana rocks.