Made a few changes today based on the excellent retail limited environment.
New Additions from FRA:

This is one I put in originally but took out before playing the Cube in paper after not being excited about it in online test drafts, but having played it a bit, I realized my initial reaction was right. Besides being one of the top uncommon performers in both draft and sealed according to 17lands data, Fblthp, Impossibly Lost is a great utility card. As I said initially, it does really play out like a Chart a Course variant that replaces incidental discard with a live-the-dream style win-condition that is totally feasible. It plays very well with the many Unearth variants I now support, too. Just a fun card that has a lot more going on than its text may suggest.

Again, I initially tried this out and liked it based on theory crafting but let online practice drafts undermine my gut. This plays like a Custodi Lich as I mentioned before, but also feels like a Planeswalker in a way that modern 'walkers have largely failed to do with the power creep of the last few years.

I don't agree with the idea that The Theorist, Jace Beleren is the modern equivalent of Jace, the Mind Sculptor, but it fits a similar enough role that I understand where folks are coming from. I didn't want to include this mostly because of the unique token/price combination, but I'm relenting since I do like blue having a powerful modern walker, and as much as I like Chandra, Chill of Compliance (and I do!!), The Theorist is more of a general-use 'walker that any blue deck will want, which, for a Cube my size, is generally a good thing.

Uldaros Theorix is an inclusion more as a recognition that, even in artifact-centric builds, I'm just not terribly inspired to play/draft Tezzeret, Agent of Bolas. Uldaros reminds me of how Dragonlord Silumgar played ten years ago.

I was initially completely baffled by the excitement around this card as a worse Think Twice/Plunder the Trollshaws, and thought the cleanness of Abandon Attachments was similarly preferable. However, I was wrong. Even without Snapcaster in retail (well, kind of), there, it's just such a flexible and powerful card draw spell that also lets you get discard going.

I really didn't want to include this card exclusively because of the art. The value of this card is undeniable, though. I just...it's so valuable in my Cube with all the discard in Red. The haste is actually a big deal here too. Again, as I continue to add more Unearth variants, this kind of card just gets better and better, making for fun chains of recursion.


I am going to go in on these. Bringing back my boy Vito, Thorn of the Dusk Rose for the test too. I'm not sure how long they'll stay, but regardless of Ajani's mediocre retail performance, the card is undeniably fun to play and I think will do reasonably well as both a signal to my drafters and a novel planeswalker that plays along a slightly different axis. Enlightened Confidant may be a little too hard to grok the first read through, but the way it plays out is exceptional. Worth the test, I think/hope, and it lets me justify keeping in Sorin of House Markov a little longer.

Sanctum Lurker missed my first pass because it said "empower Jace" without reminder text. Even with it, I only have five cards in my 720-card Cube that mention the mechanic. I think it's really annoying that it doesn't explain what it does on the card, but to be fair, there's a ton of text to the mechanic. I understand why many Cube curators are avoiding it altogether. However, for my sake, I really do think empowering Jace is beyond cool and plays great. The knobs are tuned perfectly. The value is generally incidental, but it creates the dynamics I feel I've been looking for out of planeswalkers this whole time. I wasn't the biggest fan of them when they first hit the scene, but I've really grown to appreciate them and find them to be compelling game pieces, and I'm so glad they figured out a way to use the mechanic in retail limited in a way that makes sense for commons, as opposed to the Cube-light experience that WAR gave us with one-per-pack.
But as for the Lurker in general, I like the draining ability he gives the Jace tokens (and your others!) and alludes to a super friends deck. In my Cube, that's never been harder to pull off, but I think having that dream available to live is worth one card out of 720, and I think the card works just great in isolation, holding its own against my other 3-drops. Do I wish I could justify my darling Haakon, Stromgald Scourge in this slot? More than anything. But I will be satisfied with the Lurker in the meantime.
Validation:

Yeah, this card is sweet as hell. Only needing two things to die, and not even just from your side of the board, makes Darklight Phoenix a super Bloodghast that feels like it was made for Cube.

Sphinx of False Conclusions is part combat trick, part finisher, part graveyard-filler, part wrath protection. I really prefer this kind of protection to things like hexproof or shroud, and in this case, it's both better and more exciting/interesting than Ward, too. Getting a second wind with your flashing flier feels great, but it's not wholly unsurmountable. Katara, Waterbending Master and my recent pet favorite Fire Nation Occupation both love having so many new threats with flash too.

Lyra, Tolarian Archangel was originally my favorite card of the set, and the way she's played out has only validated that further. In retail, sure, you're going to use her activated ability a lot more frequently. But I've done countless practice drafts / IRL games where she's been a dream, too. Very fun build-around that asks exactly the right amount from you during draft/deck construction.

Proft, Sinister Mastermind was another of my top picks and continues to be so. A 3mv 5/5 menace feels like you're cheating sometimes in retail but makes a lot more sense in Cube. The removal aspect is expectedly weak, but works just fine as an unexpected combat trick, then giving Proft a second life as a juicy unearth target.

I had high expectations for Samut, Hazoret's Champion but she's played out even better than expected. There was a long while where I kept Urabrask the Hidden around long after it had seen its best glory days simply for the fires ability stapled to a creature, and while I recently added in Enduring Courage, there's something truly magical about having this ability at just 2mv on a dude. Retail draft makes this card insane, both while curving out and if you hold her back in the mid-to-late game for an explosive turn. Simple, straightforward, and cool as hell, this is a Cube card that should survive for quite some time.

I've talked a lot about Way of the Pyromancer and I feel incredibly vindicated. While I'm not willing to go full Big Red Super Friends with Ajani Unrelenting as the top end (I think the card is a little too oppressive/anti-fun for my power-level, and absolutely is in retail), I may end up returning long-time favorite Chandra, Acolyte of Flame back into my list, even if the Jace token isn't technically red itself. Way of the Pyromancer is just fine in retail limited, and loses a lot of its punch if played after turn 2, but I think people still play it wrong/undervalue it. Many of the best and most expensive threats in the format are red, including the Mythic Uncommon Kiora of Fire and Ashes, who is quite mana-hungry even after you ramp up to her. In Cube, though, Way of the Pyromancer is everything I hoped Sarkhan, Fireblood to be for a whole mana less. Easily still one of my favorite cards of the set.
Underperformers:

I knew this card would be at best a tier-2 piece of removal but its cleanness and the way it read made me very excited for it. I liked how it gave a boost to +1/+1 counters and equipment. That said, there are just too many counters running around in my Cube. Whereas GftT and Doom Blade hit ~85%+ of creatures, this has been a little more problematic in retail draft than that. I think those are good baseline comparisons for a tier-2 piece of removal, and it doesn't even have the advantage of being 1 mana like things like Bloodchief's Thirst.

I was a little more surprised by this one, but I shouldn't have been. Giving a card just feels really bad, as you don't want to give many dudes the option to attack you before you take him out, and gifting a whole-ass card is so much worse than a clue or a couple of maps.

I still think Dark Matter Manipulator is fine, but even though it performs ok in the self-mill heavy environment of FRA Retail, it feels just a little too weak for my Cube and I'm surprised how much attention/pick-up it's gotten. Making it a 3/2 for 1 isn't that hard, but Putrid Imp seems like a better card in most lists from how I've seen this play out. I'll stick with Stitcher's Supplier.
New Additions from FRA:
This is one I put in originally but took out before playing the Cube in paper after not being excited about it in online test drafts, but having played it a bit, I realized my initial reaction was right. Besides being one of the top uncommon performers in both draft and sealed according to 17lands data, Fblthp, Impossibly Lost is a great utility card. As I said initially, it does really play out like a Chart a Course variant that replaces incidental discard with a live-the-dream style win-condition that is totally feasible. It plays very well with the many Unearth variants I now support, too. Just a fun card that has a lot more going on than its text may suggest.
Again, I initially tried this out and liked it based on theory crafting but let online practice drafts undermine my gut. This plays like a Custodi Lich as I mentioned before, but also feels like a Planeswalker in a way that modern 'walkers have largely failed to do with the power creep of the last few years.
I don't agree with the idea that The Theorist, Jace Beleren is the modern equivalent of Jace, the Mind Sculptor, but it fits a similar enough role that I understand where folks are coming from. I didn't want to include this mostly because of the unique token/price combination, but I'm relenting since I do like blue having a powerful modern walker, and as much as I like Chandra, Chill of Compliance (and I do!!), The Theorist is more of a general-use 'walker that any blue deck will want, which, for a Cube my size, is generally a good thing.
Uldaros Theorix is an inclusion more as a recognition that, even in artifact-centric builds, I'm just not terribly inspired to play/draft Tezzeret, Agent of Bolas. Uldaros reminds me of how Dragonlord Silumgar played ten years ago.
I was initially completely baffled by the excitement around this card as a worse Think Twice/Plunder the Trollshaws, and thought the cleanness of Abandon Attachments was similarly preferable. However, I was wrong. Even without Snapcaster in retail (well, kind of), there, it's just such a flexible and powerful card draw spell that also lets you get discard going.
I really didn't want to include this card exclusively because of the art. The value of this card is undeniable, though. I just...it's so valuable in my Cube with all the discard in Red. The haste is actually a big deal here too. Again, as I continue to add more Unearth variants, this kind of card just gets better and better, making for fun chains of recursion.
I am going to go in on these. Bringing back my boy Vito, Thorn of the Dusk Rose for the test too. I'm not sure how long they'll stay, but regardless of Ajani's mediocre retail performance, the card is undeniably fun to play and I think will do reasonably well as both a signal to my drafters and a novel planeswalker that plays along a slightly different axis. Enlightened Confidant may be a little too hard to grok the first read through, but the way it plays out is exceptional. Worth the test, I think/hope, and it lets me justify keeping in Sorin of House Markov a little longer.
Sanctum Lurker missed my first pass because it said "empower Jace" without reminder text. Even with it, I only have five cards in my 720-card Cube that mention the mechanic. I think it's really annoying that it doesn't explain what it does on the card, but to be fair, there's a ton of text to the mechanic. I understand why many Cube curators are avoiding it altogether. However, for my sake, I really do think empowering Jace is beyond cool and plays great. The knobs are tuned perfectly. The value is generally incidental, but it creates the dynamics I feel I've been looking for out of planeswalkers this whole time. I wasn't the biggest fan of them when they first hit the scene, but I've really grown to appreciate them and find them to be compelling game pieces, and I'm so glad they figured out a way to use the mechanic in retail limited in a way that makes sense for commons, as opposed to the Cube-light experience that WAR gave us with one-per-pack.
But as for the Lurker in general, I like the draining ability he gives the Jace tokens (and your others!) and alludes to a super friends deck. In my Cube, that's never been harder to pull off, but I think having that dream available to live is worth one card out of 720, and I think the card works just great in isolation, holding its own against my other 3-drops. Do I wish I could justify my darling Haakon, Stromgald Scourge in this slot? More than anything. But I will be satisfied with the Lurker in the meantime.
Validation:
Yeah, this card is sweet as hell. Only needing two things to die, and not even just from your side of the board, makes Darklight Phoenix a super Bloodghast that feels like it was made for Cube.
Sphinx of False Conclusions is part combat trick, part finisher, part graveyard-filler, part wrath protection. I really prefer this kind of protection to things like hexproof or shroud, and in this case, it's both better and more exciting/interesting than Ward, too. Getting a second wind with your flashing flier feels great, but it's not wholly unsurmountable. Katara, Waterbending Master and my recent pet favorite Fire Nation Occupation both love having so many new threats with flash too.
Lyra, Tolarian Archangel was originally my favorite card of the set, and the way she's played out has only validated that further. In retail, sure, you're going to use her activated ability a lot more frequently. But I've done countless practice drafts / IRL games where she's been a dream, too. Very fun build-around that asks exactly the right amount from you during draft/deck construction.
Proft, Sinister Mastermind was another of my top picks and continues to be so. A 3mv 5/5 menace feels like you're cheating sometimes in retail but makes a lot more sense in Cube. The removal aspect is expectedly weak, but works just fine as an unexpected combat trick, then giving Proft a second life as a juicy unearth target.
I had high expectations for Samut, Hazoret's Champion but she's played out even better than expected. There was a long while where I kept Urabrask the Hidden around long after it had seen its best glory days simply for the fires ability stapled to a creature, and while I recently added in Enduring Courage, there's something truly magical about having this ability at just 2mv on a dude. Retail draft makes this card insane, both while curving out and if you hold her back in the mid-to-late game for an explosive turn. Simple, straightforward, and cool as hell, this is a Cube card that should survive for quite some time.
I've talked a lot about Way of the Pyromancer and I feel incredibly vindicated. While I'm not willing to go full Big Red Super Friends with Ajani Unrelenting as the top end (I think the card is a little too oppressive/anti-fun for my power-level, and absolutely is in retail), I may end up returning long-time favorite Chandra, Acolyte of Flame back into my list, even if the Jace token isn't technically red itself. Way of the Pyromancer is just fine in retail limited, and loses a lot of its punch if played after turn 2, but I think people still play it wrong/undervalue it. Many of the best and most expensive threats in the format are red, including the Mythic Uncommon Kiora of Fire and Ashes, who is quite mana-hungry even after you ramp up to her. In Cube, though, Way of the Pyromancer is everything I hoped Sarkhan, Fireblood to be for a whole mana less. Easily still one of my favorite cards of the set.
Underperformers:
I knew this card would be at best a tier-2 piece of removal but its cleanness and the way it read made me very excited for it. I liked how it gave a boost to +1/+1 counters and equipment. That said, there are just too many counters running around in my Cube. Whereas GftT and Doom Blade hit ~85%+ of creatures, this has been a little more problematic in retail draft than that. I think those are good baseline comparisons for a tier-2 piece of removal, and it doesn't even have the advantage of being 1 mana like things like Bloodchief's Thirst.
I was a little more surprised by this one, but I shouldn't have been. Giving a card just feels really bad, as you don't want to give many dudes the option to attack you before you take him out, and gifting a whole-ass card is so much worse than a clue or a couple of maps.
I still think Dark Matter Manipulator is fine, but even though it performs ok in the self-mill heavy environment of FRA Retail, it feels just a little too weak for my Cube and I'm surprised how much attention/pick-up it's gotten. Making it a 3/2 for 1 isn't that hard, but Putrid Imp seems like a better card in most lists from how I've seen this play out. I'll stick with Stitcher's Supplier.