Swapping out some underperforming cards.

Sacred Mesa => Yes Man, Personal Securitron

Sacred Mesa isn't fulfilling the three cost slot for white. It appears to be a 3 cost, but in practice, you never want to drop it until turn 5. You essentially have to scrap your turn 4 with it if you okay on curve. Strong effect, but underwhelming to play.
Yes Man, while being a Universe Beyond card, it will force interaction, since it is essentially an Humble Defector in white that spawns an army in a can.

Skyclave Apparition => Wojek Investigator

Wojek Investigator adds more investigate/token support. Skyclave Apparition is a great card, but reducing more removal, this will allow the W/X players to have another path to keep up the other players.

Galazeth Prismari => Cutthroat Negotiator

Galazeth is on theme, but maybe a little too narrow. Not enough big mana instants/sorceries to justify the confusion of making sure people aren't trapping their tokens for spells. Cutthroat Negotiator is more in line where I want the future of Izzet in the cube to be.

Cryptbreaker => Tinybones, the Pickpocket

Cryptbreaker was underperforming, and the new Tinybones to seems to be fun. It's an even CMC swap, even slots in with Dimir theft.

Weatherlight Compleated is a little too slow and inconsistent for what I want. Contested Game Ball might make for more....contested Game state.

Discerning Financier fills a role that keeps white up with mana resources/card draw and adds an interesting dynamic in a multiplayer setting. Gonna see how it fits. Losheel is likely too narrow to really get snapped up quickly while Discerning Financier can be slotted into any W/X deck and may even be desired as a splash in R/G Treasures

Now that I've got a 360 list, I can make changes with 1 to 1 swaps.

An Offer You Can't Refuse => Filter Out

• I never really wanted to have too many counterspells in this cube, and a narrow one like An Offer You Can't Refuse is nice when you need it, but it can feel pretty useless in a creature heavy environment. Filter Out lets you deal with artifacts, enchantments and walkers for a turn, giving U/X decks a chance to stabilize in the midgame.

Old Gnawbone => Wolfbriar Elemental

• Old Gnawbone really doesn't fit. It costs too much mana, and green was already too top heavy to begin with. Wolfbriar Elemental gives G/X decks a mana sink in the late game and slots in nicely with G/W token strategies while evening out green's curve. (I didn't want to buy or proxy Old Gnawbone anyway)

Fable of Wolf and Owl=>Hydroid Krasis

• This was a pretty simple swap. I'm still trying to figure out what to do with simic other than just being valuetown. Fable is just a little too slow for the cost. Hydroid Krasis can help stabilization and give players something to cast in the late game that can give them gas to go for a win.

Etched Familiar => Ebondeath, Dracolich

• Evening out black's curve. Etched Familiar is neat, but Ebondeath will allow black decks to always have a creature to work with for various strategies, or just as a recurable threat.

Generous Gift => Sky Crier

• This swap hurts a lot, it might be temporary. White has too much removal at 3, and could use more mana sinks and card draw. Sky Crier does this and more. Generous Gift might come back later, but not in Sky Crier's place.

Mukotai Soulripper => Underworld Connections*

• More curve evening. Mukotai Soulripper seems too slow for arisocrat strategies, so swapping for more card draw to keep the games moving.

Dodgy Jalopy => Esika's Chariot

• Just a power upgrade. Going forward the bar for vehicles will be higher. I love them as a concept, but they need to be draftable by any player, not just someone leaning into vehicle synergies.

Lifecrafter's Bestiary => Abundance

• A conceptual swap for the later points in the game. When you don't want lands anymore, you won't get lands anymore. Should be helpful against late game stalls in G/X.

Card Swaps

• After some thinking, I don't think Mogis would lead to very fun or interesting games without plentiful exile removal, which I do not want to add. Juri is on theme for what Rakdos wants to do and can lead to some interesting game states with the potential of damage crackback if removed.

• Blue was lacking in board wipes and probably doesn't need a second windfall effect.