I've slotted a few more cards from Phyrexia: All Will Be One into this cube.

Fireblade Charger replaced by Cacophony Scamp
These are very, very similar cards. Ultimately I think Cacophony Scamp's Proliferate effect is more what this environment wants than Fireblade Charger's conditional Haste.

Eligeth, Crossroads Augur replaced by Serum Sovereign
As I mentioned in my previous post I'm trying to get rid of this cube's Scry subtheme. I replaced Eligeth with Serum Soverign", a card that plays better with this cube's Izzet "Non-Creatures Matter"

Scorchwalker replaced by Vindictive Flamestoker
While I love Bloodrush cards, I think Scorchwalker simply isn't very strong. I've swapped Vindicative Flamestoker in which is a much more relevant card.

Viashino Shanktail replaced by Urabrask's Forge
While not quite as underwhelming as Scorchwalker, Viashino Shanktail is another Bloodrush card that just wasn't pulling its weight. Urbrask's Forge is just generally a much more fun card, especially the way it interacts with Proliferate.

Sage's Row Savant replaced by Atmosphere Surgeon
Another scrying card cut as I cut the subtheme. I like having a "non creature spells matter" theme that ties into Oil Counters. Non-Creature spells being used to generate Oil Counters ties them more closely into the "wacky counters" vibe this cube is going for.

Vivisurgeon's Insight replaced by Trawler Drake
Even though I only recently added Vivisurgeon's Insight, spending 5 mana to draw 3 just isn't very good, even with Proliferate stapled on. I swapped the card out for Trawler Drake to expand my Oil Countery//Non-creature spelly theme. Do I have too many 3 drop flyers now? Who knows...

Crystalline Giant replaced by Atraxa's Skitterfang
Crystalline Giant is just a logistically difficult card to work with. A fun card, but one that's difficult to use outside of digital play. I've swapped the giant out for Attraxa's Skitterfang which fulfils a similar function, but without the need to choose ability counters randomly and roll 10 sided dice.

Skyclave Shadowcat replaced by Archfiend of the Dross
I don't really have anything to make sacrificing matter in this cube, so Skyclave Shadowcat was always a bit of an anomaly. Archfiend of the Dross, in contrast, is a very fun risk vs reward card that I am eager to try out.

Makeshift Battalion replaced by Bladed Ambassador
Two drops are generally better to have around than three drops, especially for aggressive decks. Makeshift Battalion just wasn't a card that players were excited to run, I hope Bladed Ambassador will be more appealing.

Josu Vess, Lich Knight replaced by Scheming Aspirant
I really want to try Scheming Aspirant in this cube. Even though Black doesn't have a huge number of Proliferate cards I still think Scheming Aspirant will encourage some interesting deck building decisions when splashing other colors. Not 100% certain that cutting Josu is the right call, but it's the card I'm currently going with. Will potentially reflect on this later and swap Josu back in.

Phyrexia All Will Be One gave this cube a lot of new toys, especially in Blue.

Elvish Visionary replaced by Contagious Vorrac.

The Visionary is just a generic card that goes into lots of Cubes, the Vorrac fits in better with my themes and provides a similar function.

Prophet of the Peak replaced by The Filigree Sylex.

Prophet of the Peak wasn't really contributing much to this cube. Given that this cube is all about "wacky counters" The Filigree Sylex puts Oil Counters into the mix and just fulfils a more useful function.

Dissolve replaced by Reject Imperfection
This cube has a bit of a "scry matters theme" in Mono Blue which I'm thinking of just cutting. I swapped Dissolve for Reject Imperfection, as Reject Imperfection plays into my far more prominent Counters theme.

Bloom Hulk replaced by Adaptive Sporesinger
Adaptive Sporesinger is just a lower cost version of Gloom Hulk which also Provides more versatility. Cubes work better with lower curves.

Contentious Plan replaced by Experimental Augury
Contentious Plan is a pretty weak card, Experimental Augury offers a strictly better version of the effect with power more in line with what I'm looking for.

Scavenged Blade replaced by Barbed Batterfist
Scavenged Blade requires a creature in play to set up "modified", Barbed Batterfist can set up "modified" all by itself.

Risona, Asari Commander replaced by Bladehold War-Whip

While Indestructable Counters definitely qualify as "wacky counters" and it pains me slightly to remove a card with them, ultimately this feels like the right call. Risona doesn't really synergise with anything else Red/White is doing in this cube, whilst Blade-Hold War-Whip definitely doe, providing both a creature token with Double Strike to buff up and a discount on future equip costs.

Siani, Eye of the Storm replaced by Hurkyl, Master Wizard
Siani only really players into "flyers matter" and "scry matters" neither of which are very prominent subthemes in my cube. Hurkl, makes an interesting addition to Red/Blue "non-creatuers matter" strategies. I am concerned that this card is a bit hard to parse though.

Murder replaced by Drown in Ichor
Tamiyo's Epiphany replaced by Vivisurgeon's Insight
Charmed Sleep replaced by Mesmerizing Dose
Into the Roil replaced by Serum Snare

These are all instance of replacing generic spells, with spells that Proliferate. It's a shame because I find some of the Phyrexian art a little gory and grim, but the effects on the cards just work better for the cube.

Thinking of potentially adding a Scheming Aspirant in future.