Expect to be good: Archfiend of Sorrows - Very solid card and a rare 7 drop worth including Scurry Oak - Evolve is great, squirrels are great, repeatable token makers are great Flametongue Yearling - Harder to splash buffed Fire Imp
Good archetype support, if a bit boring: Barbed Spike - Good all around archetype support (aggro, flyers, pants, tokens, artifacts) and just a solid card in general Legion Vanguard - Sac outlets that don't need to combo to be good are rare Sinister Starfish - Filtering yay Arcus Acoltye - All 4 abilities sound good even if I have doubts about outlast Abundant Harvest - Filtering yay
High hopes, but probably just okay: Squirrel Sanctuary - Reasonably efficient with decent synergy Blazing Rootwalla - Not sure how good the buff is or if delaying for madness is worthwhile Captain Ripley Vance - Exciting card
Barbed Point is finally an upgrade to some really old cards. Also free pants support.
Tireless Provisioner is a great dedicated ramp card with repeatable lifegain + storable mana, but not accelerating 4 drops and trading down on mana vs removal makes it way worse elsewhere.
With how multicolour friendly our duals are Glinting Creeper isn't that hard to get big. A 5 mana 8/8 isn't too unrealistic, though it is a bit boring.
Arcus Acolyte having lifelink and reach on a growing body as well as a build your own anthem seems pretty solid. That being said, I'm a bit hesitant since I was not impressed by outlast in the past. Obviously great if you support +1/+1 counters.
Captain Ripley Vance is a sick card. Getting 1 trigger isn't super easy, but obviously makes the card excellent. Also Reckless Charge + flashback + spell is lethal on an open board (if that spell is Temur Battle Rage it's lethal against <11 toughness boards).
Herd Baloth might be justifiable with only heavy combo support. It and Scurry Oak go infinite with Ivy Lane Denizen, but they both also work with the +1/+1 on etb cards that enable the persist combo. Renata, Called to the Hunt, Grumgully the Generous, Good-Fortune Unicorn, and Rhythm of the Wild are 4 entirely reasonable cards that turn Herd Baloth into 2 5/5s. It's a lot of specific cards, but even just in RG you can have 4 enablers, 2 Ivy Lane specific pieces, 2 persist creatures, then Goblin Bombardment + alternate sac outlet of choice, which is a lot of redundancy for infinite combos that is playing reasonable midrange cards.
Prophetic Titan being expensive and needing delirium makes it a bit hard to recommend over most UR cards that see play but it is an incredibly abusable card with a bit of work. Using the etb impulse to find reanimation/blink effects makes it into a single card engine in the right deck (It + Ephemerate is reasonably close to lethal by itself). Without blink/reanimation I think its powerlevel doesn't make up for how much more expensive and clunky it is than most played UR cards.
Is a third regrowth effect in Timeless Witness worth playing at 360? Or is it better than Eternal Witness / Regrowth? Even playing more than one in a deck feels pretty slow.
Lose Focus is a good counterspell. Imitating a hard counter while also being able to be cast for 2 is really nice.
Blazing Rootwalla is pretty good. 3/1 is big enough aggressive midrange decks could easily play it. With some discard it's actively worth playing and even without discard it's solid curve filler.
Needing to trigger delirium on Dragon's Rage Channeler to get the payoff of a 1 mana 3/3 flyer with a downside just isn't that good in most decks. The surveil is nice but is most impactful late in the game, which goes against how aggressive the payoff is. There's certainly some decks that want this card, but in general aggro doesn't like its inconsistency and dedicated spells matter builds have better (and less fragile) payoffs.
Junk Winder is great but entirely in the wrong colour. In blue it's pretty heavily restricted to Whirler Rogue/Talrand's Invocation/Kasmina, Enigmatic Mentor, which makes it incredibly dependent on other colours while being CC and having an incredibly bad worst case. If it was 6U I would probably test it with the intention of mainly splashing it, but that's not really doable with 5UU.
Scurry Oak being able to go infinite in mono-g with only 2 cards is pretty neat, especially considering both are alright by themselves. Without synergies you're looking for 2 triggers for it to be great, which is pretty reasonable. Admittedly 1/2 evolve is way more awkward than Crocanura's 1/3 evolve, so I could see it being too clunky.
Jade Revenge Frog is a pretty boring beater. Blocks, gets in for 2, and has 2 words of rules text.
Abundant Harvest is a good card. Only awkward thing is that it's purely consistency, whereas the blue cantrips easily support spells matter.
Ravenous Squirrel being hybrid is nice if there's ever enough aristocrat support in green. The ability can pretty easily be splashed off of vivids/tris/thrivings, which is a big plus.
I kinda like Squirrel Sanctuary. 1 to play and 1 to return is really nice for mana efficiency. 2x+1 mana for x+1 bodies is a good rate in green, which is pretty relevant since green has the best anthems by a good margin. Squirrel Nest and Sprout Swarm are more efficient, but neither of them work if you're trying to Song of Freyalise, Scale Up, and/or Ridgescale Tusker on t5-6 or play white stuff like Relief Captain. Also has a bunch of minor interactions with stuff like Kor Skyfisher/Clarion Spirit/enchatress effects/discard costs/prowess/etc..
Young Necromancer seems too expensive unless if you're blinking it. ~2 more mana for a 2/3 is okay CA, but 5 drops and reanimation are both pretty clunky.
Obviously a great card. Multikicker and interaction with pump spells makes it more interesting (and better) than Fire Imp. CC preventing splashing also helps avoid 3+ colour goodstuff.
Archfiend of Sorrows - Very solid card and a rare 7 drop worth including
Scurry Oak - Evolve is great, squirrels are great, repeatable token makers are great
Flametongue Yearling - Harder to splash buffed Fire Imp
Good archetype support, if a bit boring:
Barbed Spike - Good all around archetype support (aggro, flyers, pants, tokens, artifacts) and just a solid card in general
Legion Vanguard - Sac outlets that don't need to combo to be good are rare
Sinister Starfish - Filtering yay
Arcus Acoltye - All 4 abilities sound good even if I have doubts about outlast
Abundant Harvest - Filtering yay
High hopes, but probably just okay:
Squirrel Sanctuary - Reasonably efficient with decent synergy
Blazing Rootwalla - Not sure how good the buff is or if delaying for madness is worthwhile
Captain Ripley Vance - Exciting card
Thoughts on Unbounded Potential?
Tireless Provisioner is a great dedicated ramp card with repeatable lifegain + storable mana, but not accelerating 4 drops and trading down on mana vs removal makes it way worse elsewhere.
With how multicolour friendly our duals are Glinting Creeper isn't that hard to get big. A 5 mana 8/8 isn't too unrealistic, though it is a bit boring.
Arcus Acolyte having lifelink and reach on a growing body as well as a build your own anthem seems pretty solid. That being said, I'm a bit hesitant since I was not impressed by outlast in the past. Obviously great if you support +1/+1 counters.
Captain Ripley Vance is a sick card. Getting 1 trigger isn't super easy, but obviously makes the card excellent. Also Reckless Charge + flashback + spell is lethal on an open board (if that spell is Temur Battle Rage it's lethal against <11 toughness boards).
Rakdos Headliner is an excellent BR aggro card.
Prophetic Titan being expensive and needing delirium makes it a bit hard to recommend over most UR cards that see play but it is an incredibly abusable card with a bit of work. Using the etb impulse to find reanimation/blink effects makes it into a single card engine in the right deck (It + Ephemerate is reasonably close to lethal by itself). Without blink/reanimation I think its powerlevel doesn't make up for how much more expensive and clunky it is than most played UR cards.
Is a third regrowth effect in Timeless Witness worth playing at 360? Or is it better than Eternal Witness / Regrowth? Even playing more than one in a deck feels pretty slow.
In the average cube Abiding Grace probably needs to be targeting Thraben Inspector/Mother of Runes/Thoughtpicker Witch/Carrion Feeder to worthwhile. Given the inconsistency problems on top of that it's probably too narrow.
Lose Focus is a good counterspell. Imitating a hard counter while also being able to be cast for 2 is really nice.
Blazing Rootwalla is pretty good. 3/1 is big enough aggressive midrange decks could easily play it. With some discard it's actively worth playing and even without discard it's solid curve filler.
Junk Winder is great but entirely in the wrong colour. In blue it's pretty heavily restricted to Whirler Rogue/Talrand's Invocation/Kasmina, Enigmatic Mentor, which makes it incredibly dependent on other colours while being CC and having an incredibly bad worst case. If it was 6U I would probably test it with the intention of mainly splashing it, but that's not really doable with 5UU.
Jade Revenge Frog is a pretty boring beater. Blocks, gets in for 2, and has 2 words of rules text.
Abundant Harvest is a good card. Only awkward thing is that it's purely consistency, whereas the blue cantrips easily support spells matter.
I kinda like Squirrel Sanctuary. 1 to play and 1 to return is really nice for mana efficiency. 2x+1 mana for x+1 bodies is a good rate in green, which is pretty relevant since green has the best anthems by a good margin. Squirrel Nest and Sprout Swarm are more efficient, but neither of them work if you're trying to Song of Freyalise, Scale Up, and/or Ridgescale Tusker on t5-6 or play white stuff like Relief Captain. Also has a bunch of minor interactions with stuff like Kor Skyfisher/Clarion Spirit/enchatress effects/discard costs/prowess/etc..
Young Necromancer seems too expensive unless if you're blinking it. ~2 more mana for a 2/3 is okay CA, but 5 drops and reanimation are both pretty clunky.