Wanting to push more Prowess. Already added Bedlam Reveler, now I want to slow down the red decks a little, while also providing more instants and sorceries.
Monk of the Open Hand -> Optimistic Scavenger
Scavenger is a good way to enable modified and is a decent cheap pay off for heroic strategies. I want to move away from the Flurry theme at the moment and focus on some of the core archetypes of the cube. I'm considering making a second cube to try out that archetype.
Stonebinder's Familiar -> Fumigate
The first thing that was obvious from the first play test was that control did not have nearly enough tools. Fumigate will add another sweeper in white to hopefully punish aggressive decks for overcommitting.
Lantern Bearer -> Wingspan Stride
Wingspan seems like a more interesting version of this effect, allowing the controller to retrigger heroic/valiant and move around evasion.
Outlaw Stitcher -> Baral's Expertise
Expertise here gives blue some ability to deal with aggressive decks in the late game.
Fear of Isolation -> Twist Reality
Blue needs better interaction. This will give them a hard counter spell, or an instant speed body that can fill the graveyard.
Ordeal of Thassa -> Kasmina, Enigmatic Mentor
Ordeal was a bit clunky and slow to get it's pay off. I'm wanting to test out Planeswalkers but ones that don't take over a game. I'm a big fan of the uncommon walkers from War of the Spark. These should also help Delirium strategies a little.
Boneyard Mycodrax -> Qarsi Revenant
Mycodrax felt a little awkward with all of the ways to exile cards from the graveyard, yet still wanting to have delirium. Revenant is similar, but doesn't require the yard full of creatures to activate and give you a big modified threat.
Scourge of Nel Toth -> Crabomination
Crab is just way more interesting as a control finisher and threat and actually gives the caster a huge card advantage swing for casting it.
Skinrender -> Night Incarnate
Night Incarnate is similar in being a body that can act as removal, but it has better base stats and Deathtouch, while also being able to kill all creatures with toughness 3 or less.
Arcbound Tracker -> Feldon of the Third Path
Feldon is very strong. It's more of a self contained card that hopefully creates some fun decks built around it.
Reckless Bushwhacker -> Trumpeting Carnosaur
Giving control more tools while raising the curve.
Maximize Velocity -> Channeled Dragonfire
Super interested in the power-matters flashback mechanic that is Harmonize for this cube. This seems decent enough to warrant inclusion.
Geological Appraiser -> Songcrafter Mage
A 3-color card breaks with convention, but this card is too sweet not to try.
Rise of the Varmints -> Willow Geist
This creates a unique token and is basically the same effect as Spider Spawning, but less powerful.
Pawpatch Formation -> Heritage Reclamation
Virtually a 1 for 1 replacement, but I like the graveyard hate a bit more than the food token.
Monk Class -> Inquisitive Glimmer
Oji, the Exquisite Blade -> Staggering Insight
Want to shift focus back to heroic for UW for now.
Old Rutstein -> The Swarmweaver
A better Delirium enabler and has awesome synergy with Spider Spawning.
Malcolm, the Eyes -> Glacial Dragonhunt
Sweet card draw and discard with built in removal.
Shardless Agent -> Vilespawn Spider
Tempest Hart -> Tamiyo, Collector of Tales
Ivy, Gleeful Spellthief -> Kishla Skimmer
Focus Simic back into being about graveyard synergies.