Part three is before part one and I have entirely failed to get it in order...
Marwyn, the Nurturer 1
I'm not even sure I would run this in an elf deck. It is a three mana 1/1 that needs to get to the untap step before it does anything and it really also needs follow up to perform. There is no world in which I play this over a card like Priest of Titania or the Archdruid. Gyre Sage and Channeler Initiate also both seem preferable.
Seal Away 6
Black has a lot of Assassinate effects but mostly they are sorceries. The value of killing tapped creatures goes up massively when your card has flash. Reciprocate is a terrible card while Condemn is a great one. You don't want to have to take a hit for your removal to work and that is why Condemn is so much better than Reciprocate and why Death Stroke is a limp card. I have never much liked Journey to Nowhere nor even Oblivion Ring cards however I love Cast Out. I feel I will like Seal Away in the way I do Cast Out. Tthe advantage you get out of removal, particularly clunkier removal, is massively increased when it can be used as an instant. The tempo gains are substantially better overall and I think it is that aspect that makes me like this a lot more than Journey despite having similar overall power level. Jouney always felt very restrictive as you wouldn't ever want to try and gain a bit of tempo with it against a dangerous target with a good EtB effect. That risk somehow feels offset by the instant speed even if it doesn't really directly compensate or help with that issue. One issue with Seal Away is that it is bad against creatures with on attack triggers. Most notably the Titan cycle but plenty of other cards like Hanwier Garrison have it too. That might be inconvenient enough to gazump Seal Away's cube chances.
Naru Meha, Master Wizard 3
I think playing this as a Fork (Twincast) will lead to great disappointment. Four mana to use and only able to hit your own stuff makes this super unlikely to get that much value. Late game you are unlikely to have Ponder style cheap cards still in hand and so really this is just a wizard lord. A flash Hill Giant is kind of OK, you don't play it outside of a wizards deck but it is probably plenty good enough without the fork aspect to run in some tribal build.
Settle the Score 0
This is just a very bad Vraska's Contempt. Lower range missing walkers and lower functionality at sorcery speed. While 2 loyalty is a lot better than 2 life the latter is always possible while the former feels very inconsistent and rather win more. Four mana removal has to be supreme and this is not even close.
Keldon Warcaller 1
A Bear with a very narrow ability. With what we have presently this is not only super narrow but also not all that impressive power wise. One day there may be enough good sagas to empower this but that is not a thing we should be holding out for.
Ancient Animus 2
A fairly average fight card that might just about rise to the top of the pile with enough legendary targets. Green is not short of such cards and this is too wishful to really be a contender.
The Mirari Conjecture 2
This can net a whole lot of value. Even if you just get back a Ponder and an Opt and you save them till the 3rd lore counter trigger then you get a four for one and decent chunk of card quality. This is comically unplayable in my drafting cube. No one plays Tidings... Where this might have a shot is in a Replenish themed deck where you can cheat out the Conjecture and it can help recur key combo components. Niche to say the least but still more useful than a lot of cards! It is too slow for a storm deck but if you could somehow get the third phase on command it might then not be too slow. Fork all the things for a turn for no extra cost per Fork is quite a nutty effect.
Whisper, Blood Liturgist 1
Like a Goblin Welder for creatures but cost and balanced accordingly and therefor not all that exciting. Really if I am looking at this I am playing Recurring Nightmare and Victimize long before hand. The body of this just makes it slow and unreliable.
Haphazard Bombardment 0
Triple Vindicate sounds nice but with it only being one a turn and also being low odds each time to hit the thing you want most to hit and that prohibitive six mana price tag this just isn't close to a thing. Nice design and flavour though.
Sporecrown Thallid 3
No use anywhere but a tribal fungus deck and obviously now I will be doing such a thing at some point down the line. I expect the deck to suck rather but a two mana lord is always a strong card within their tribe.
History of Benalia 6
Probably a bit slow and fair to be a great card but I am rather drawn to it. A pair of 2/2 vigilance dorks is an OK deal for 3 mana and a number of white decks would happily go for some of that. The delay on the second knight certainly lowers the initial kick of the card but I suspect the final trigger more than makes up for that. Getting +4 power, perhaps even 6 or 8 if you have a knight heavy board is getting towards Overrun territory. That little surge in board pressure will be nice and swingy. This is certainly a saga to test. It feels a bit fair but it is exactly the sort of card that could really out do expectation a lot. I remember how non-plussed I was about Lingering Souls when it was spoiled, I compared it to a gold (and thus narrow) Call of the Herd. Suffice it to say that Lingering Souls is one of the best cards in my cube now and is one of the most a card has outperformed my initial review. History of Benalia is certainly no Lingering Souls but it could well outperform expectation in the same kind of way.
Wizard' Retort 2
We have a lot of these Stoic Rebuttal / Silumgar's Scort style cards on offer now. Neither of those did much to impress in cube but then both of those are much harder to fulfill. Wizards are rather more prolific than dragons in cube and at least a third as common as artifacts! I still don't think I rate this that much for cube. Cancel is a limp card and Retort will be that most of the time. Either you want hard counters or you want cheap ones and you make your choices accordingly. Retort doesn't let you control the modes very well and so I don't see why you would choose it over a Negate or even a Dissolve. It is like the Rift Bolt of countermagic. Sure, I want Lightning Bolt but I am going to play Searing Spear over Rift Bolt every day in cube despite it being able to emulate Lightning Bolt relatively often.
Demonlord Belzenlok 6
Much as I love to poo poo the big cards this one seems pretty good all round. The body gets work done with solid stats to cost ratio and both flying and trample ensuring it puts damage where it needs to go while standing up to most opposition. Realistically in cube the EtB effect is drawing you 1 non-land card, a few decks will hit 2 cards every now and again but I think 3 plus in any sort of normal cube deck will literally be a once in my cubes life type affair. I lost to blind Bloodbraid Elf into Shardless Agent into Ancestral Vision yesterday and that felt like a once ever experience. I think a contained life loss benefits the card quite a lot. Imagine if the average was 3 cards, you would have to brace for the potential to six yourself whenever you cast this and that would make it far less suitable. One issue Belzenlok has is a lack of board presence. If you are behind making one blocker, even if he is a big mean one, isn't going to save you. Especially if it smacks you in the face as well. Other good black six drops like Grave Titan, Massacre Wurm and even Noxious Gearhulk all do a lot more to stabilize the game. This guy is a bit of a Rogue Refiner but in the six slot, a kind of expendable threat. I like it but I am not sure how often you can fit in a six drop like this. It is a bit like the Time Warp style cards, great when you can cast them and something you want to play but super hard to find the deck space for them.
Warcry Phoenix 1
Four is an awful lot for a 2/2 flier even with the haste. The recursion cost is also not any real sort of discount nor is it that easy to trigger. Warcry is a poor tempo play and more of a value card but decks wanting 4 mana value cards don't typically attack with 3 other dorks. Chandra's Phoenix and Flamewake both seem more powerful and better suited to actual roles red decks need.
Multani, Yavimaya's Avatar 3
This can be made immense pretty quickly in cube with all the self mill and land ramp in green. You could make this on turn four well over a 10/10 in size. Equally, in a deck with creature ramp and no self mill this would come out as a 3/3 on the same turn! Multani has great scaling into the game but isn't a consistently powerful early game threat. Paying six mana for something that has no other impact and is just a big dork is pretty risky, it is opening yourself up to falling very behind to simple spot removal. Green top end cards that are good mitigate this by having an immediate effect (Craterhoof), making loads of tokens (Avenger and Hornet Queen), netting some value (Primeval Titan), or simply refusing to eat spot removal (Carnage Tyrant). As something to curve into Multani seems very poor being both vulnerable and requiring specific build support. You are probably better off ramping into Ghalta if you really want a fat monster. Where I see Multani having more application is in a grindy deck, perhaps with Splendid Reclamation, perhaps with Life from the Loam. That sort of thing. The ability to put lands back into hand is significant and has a lot of uses, especially with a red pairing. A recursive threat that is massive is also no bad thing. I think Multani is too narrow for general use but I think he will be an excellent tool in some really cool deck ideas.