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.