Body Dropper Kathari Bomber
This cube is not big on tokens or sacrifice, so this moves the Multi-color on at least one of those angles.
Caldaia Strongarm Saddleback Lagac
Both provide two counters. Strongarm is a 5 drop, but it has the better body, and there is always the option to Blitz
Celebrity Fencer Trusty Retriever
This guy has 3 hits for the second ability, so he's just a 4mv 3/4
Celestial Regulator Dramatic Rescue
Both the current Azorius cards fulfil the same role. They can protect one of my creatures from removal, or reset an opponents creature to remove counters. Rescue might be the better card on the reset method (By forcing them to replay the creature) but it is harder to cast, so I'm going to pull it.
Echo Inspector Thunder Drake
Not wanting to go in on a 2 spells theme.
Psionic Snoop Naiad of Hidden Coves
So Naiad was part of a back-up spellslinger sub theme, but now we're getting more counters cards at common for Blue, which was the worst color.
Raffine's Informant Ainok Bond-Kin
Not sure I'm interested in Outlast, On the fence if this is a worthy swap, but I'm interrested in Connive.
Revel Ruiner Driver of the Dead
The range of 2mv cards to hit for driver is fairly small.
Security Bypass Befuddle
Pretty obvious this was a filler card.