Kicking off these spoilers is Kaguya, the-girl-who-gets-printed-every-set-in-some-fashion, in her fourth ruler appearance. We see her making a return to her roots with a huge focus on Treasury Items. She flips for free, but can only judgment if you've put a treasury item into your field this turn. She also has the handy ability of being able to check your top card, and if its a treasury item, you can add it to hand. Plusses are always good, especially when they're on a card you start the game with, and are repeatable. You can only use it once per turn, and only during your turn, but it's still a good stream of advantage if you play your cards right.
Flipping her, you're met with a wall of text that rivals even her Moonlit Savior text box. She has no stats, and no "cannot battle" text either, so she'll act like Fox and Reflect and just sit on the field once you judgment. If you have 3 or more treasury items then she gets Barrier, so no Black Moonbeam. She also has a multitude of effects that can scale with the number of treasury items you control. Resting one lets you sap 200 ATK from a j/resonator, resting two lets you make one will, resting three lets you draw a card, resting four lets you bounce a resonator, and resting five will make her a 1500/1500 flier. Keep in mind none of these are once per turn, and there isn't a restriction on how many you can use either. Got six treasury items? Draw 2. Or maybe make 3 will you can spend on anything.
Really, I hate this kind of ruler design. A comprehensive list of non-battling utility Rulers: Kaguya Princess of the Moon, Reflect // Refrain, and Nine-Tailed Fox. Two of these are banned, one is currently a meta deck (although not as strong as it used to be). Utility Rulers, by default, have a leg-up on others just because you remove the ability to kill them via battle, and most/all of them have ways to get around effect destruction. It removes almost all counter play to the Ruler itself, and they tend to have reactive effects that they can tailor to almost any situation. R//R could do virtually anything, Fox has a toolbox of Chimeras to answer any situation with, and Kaguya is Class G's Tank on crack.
I'm not crying wolf just yet, but unless her support is just dirt, I don't see this card not impacting the meta. She offers ramp, draw, battle counterplay, and the ability to become a Behemoth. Heck, she has built-in blocker removal so she might as well say "This card cannot be blocked" if the blocker doesn't have Barrier.
Here we have her dedicated shock rock. It has the standard shock rock text, produces two colors, and counts as both basic magic stones. Its specific ability lets you check the top 2 cards of your deck when it enters the field. This lets you put any Treasury Items you see on top, the use Kaguya's Ruler ability to add them to your hand. Wombo combo. Not much else to say about it, but the ability is really generic and can go great in any deck.
Right out the gates we get a resonator that counts as a treasury item. It took the Luminaries two sets to get an Ancient Magic resonator, and even then it was just a vanilla. 500/500 with Flying for two will is good value, especially a card that rests a blocker on-attack, and rests a potential attacker on-block. And rests a card when you rest it for one of Kaguya's J-Ruler abilities. The card isn't stellar on its own, but being able to play on curve and maintain field presence while building up treasury items makes it a double whammy of a card.
Water Kimono of Twelve Parts: Official Outerwear of Croco-Shark Nation. I'm a huge fan of cards with "You can run X number of these" effects, since it makes for really interesting deck brews. Water Kimono lets you run twelve in your deck (hence the "Twelve Parts" in the name), and has a cheap cost of only one water, and an even cheaper bestow cost of resting it. The bestowed resonator gets +1/+1 for each bestowed Water Kimono, so it scales exponentially. One will give it +1/+1, two for +2/+2 (a total of +4/+4), three for +3/+3 (totalling +9/+9), and so on. Six of them will give a resonator 3600 ATK/DEF. Seven will be an OTK. Combo this with the Kaguya resonator from Legacy Lost and you're looking at a relentless chain of attacks. If you bestow it to a water resonator, however, you can flat-out win the game if you bestow all twelve Kimonos to it.
Remember all that crappy Addition support from CFC? Let's revisit those. Ancient Automaton is going to be a monster in this deck. If you have the items to make Kaguya a 1500/1500, then Automaton will be a 1400/1400 two-drop. How insane is that? Keeper of the Frozen Casket is a one-drop that gives all your Additions Barrier, so R.I.P. any Addition hate.
Mystia is pretty good for what she does. 500/500 for a three-cost are abysmal stats, but she searches a treasury item on-enter, so you can get your Kaguya pain train going early. When she dies (which she will, with those stats) you can play any three-cost or less treasury item from your hand. She essentially replaces herself on the field, but I doubt she'll be necessary to the deck. Water already has access to Summon from Memoria which, coupled with Kaguya's Ruler ability, should be more than enough ponder/search to give you a healthy flow of treasury items.
Here we have discount Horn of the Sacred Beasts. It only shuffles three back, rather than the whole graveyard, and can't refresh your stones. It's good for when/if your opponent kills off a Water Kimono or two, and you're gunning for that win condition, but overall I think this'll just serve as a low-cost warm body for Kaguya's treasury item thresholds, with the utility of being able to snipe pesky graveyard cards.
Here's the monster addition. Giving blanket destruction immunity to all other treasury items means you're safe from Heavenly Gust, the only real anti-Addition card that sees meta play at the moment. If you have two of these out, your Additions are safe from any kind of destruction. The only real out would be Lumia's Judgment, but Red/Light doesn't see much play at all so that might just end up being a niche weakness. We'll have to see once this whole set is spoiled. This moon will also sap 200 ATK from a resonator when it gets rested, doubling down on Kaguya's Rest-One ability, but it doesn't do much otherwise.
That's the last of it for today. Honestly, this deck is poised to be really strong unless some hard Addition hate comes out. Lumia's Judgment has the potential to totally shut it down and skate around almost all the protection the deck has, but its color combination and high cost will make it hard to run competitively, and this deck will definitely be packing a ton of negation since it has green access. I don't want to be a doomsayer, but Kaguya is looking very solid, especially since we have more support to see.