First up is Glorius/Faria. We didn't get any revolutionary Inheritance cards revealed this set that make her totally bonkers, but that's ok. We did get Amaterasu who is just as good, and an incredible target for Glorius' Ruler ability. There's also Sacred Komainu, which turns Faria's second ability into somewhat of a win condition by letting you drop a huge power pump for free. The Inheritance deck's game plan/win condition seems to be hyper aggressive, looking to get one or two good resonators on board (like Divine Beast of Attoractia) and flipping Faria relatively early, then abusing her second ability to get multiple ATK boosts during battle. This strategy naturally lends itself to Pricia, Beast Queen in Hiding to give you more bang for your buck, as well as cards like Shining Kirin that cantrip themselves so you don't run out of cards. There are also a couple Inheritance cards that serve as blocker removal, letting your big strikes hit their mark more consistently.
The biggest weakness this deck will have is the same all aggressive decks share, being a lack of control options and inherent advantage engine. Kirin is really the only card that replaces itself once used, so it's very easy to run out of steam and stall out. Against a control deck, which seem to be too popular, that can spell defeat. Likewise, Faria is susceptible to Black Moonbeam, and losing her and her free Inheritance effect can slow the deck to a near-halt.
While Faria might not be dethroning Fiethsing as the queen of the meta anytime soon, she's a very solid aggressive ruler, which is something the game was lacking lately. She has built-in utility with her Inheritance focus, so her usefulness scales with stronger Inheritance cards, and her God's Art stops almost everything aside from Moonbeam. If/when she finally does die, at least Glorius' ability lets you filter out Inheritance cards you can no longer use.
Valentina is a really strong idea, but suffers from a couple glaring design flaws. Her front side lends itself to a control playstyle while her J-Ruler side wants a more aggressive, wide-board style of play, and her support reflects this. Half of it is control, mostly in the form of discard and some resonator removal, while the other half focuses on token spam. This creates a rather large disconnect in what her deck is trying to do, where half of the support are token-creating floaters and the other half try to gimp the opponent somehow. The biggest issue here, though, is that all of her support is over-costed and under-powered for what they do simply because they were meant to be played with her. A huge chunk of her resonators are 1 or 2 cost more than what they should be because it's assuming you're playing Valentina (and have flipped her) so it will cost 1 less.
Cards like Illusion Wizard, Nightmare, and even Moojdart are all victims of this. The problem being Moojdart herself, who gives a 200/200 buff to all Water resonators and a separate one to all Darkness resonators, for a grand total of +400/+400 to all Water/Darkness resonators. This means your tokens will be 800/800, Illusion Wizard will be 900/900, and Nightmare will be 600/600. This puts them at a little stronger than what their cost allows for (their post-reduction cost, mind you), but the whole deck is built around "These cards are bad, but they're really good if you have Moojdart out and have flipped Valentina!" which, in my opinion, is a pretty bad game plan. Granted, her natural play style at least lends itself to supporting this strategy. Her front side increases the removal power of your control cards, letting you spend the first few turns just stalling out the opponent before you get enough magic stones to flip Valentina safely, who then reduces the cost of most of your cards, letting you swarm the board with ease.
This is remarkably similar to what Mikage tries to accomplish, however. His Ruler side is dedicated to stopping weak/cheap plays the opponent makes while building up power for an aggressive flip. Valentina's real challenge will be trying to establish herself in a meta where Mikage is the tried-and-true method of control, but I don't think that will be too hard for her. Her front side gives most of her control cards enough reach to be able to hit something that, previously, was just beyond what they could kill. Space-Time Anomaly becomes a -700/-700, which lets it hit every 2-drop and a lot of 3-drop, whereas -500/-500 couldn't kill much on its own. A 1-card answer to any 2-drop is actually really important, and she let's Endless Night become a near-guaranteed 2-for-1 since, on top of the -200 DEF it gives to the field, it will give an extra -300 DEF to one card. Take, for example, the Fiethsing matchup. Endless Night on a Gwiber would kill it, nuke the Tokens and weenies, but Guinevere would still be alive. With Valentina, that Endless Night kills Guinevere, hurting their engine even more. Double Space-Time can kill a Gwiber, too, which is convenient.
Harking back to Faria, Lilias Petal is another Ruler who is strong but whose overall usefulness rides on their direct support. For Faria it was the quality of Inheritance cards, but for Lilias it's the strength of the Chimeras he can summon. Thankfully we got some decent, and flexible, Chimeras in this set and more have been all but confirmed for future sets. Unlike Faria, though, Lilias can't function as a stand-alone body, although that can be seen as both a strength and a weakness. He can't battle and can't be destroyed, making him immune to even the dreaded Black Moonbeam, as well as almost every other form of removal. Barring Blazer, or a Final Forfeit + removal, once he's on the field, he's there to stay. Unfortunately, if he picks up too much steam in the meta, those cards will likely see a surge in play to deal with him.
The best part about the Chimeras is that they can be summoned from your side deck, so you don't have to worry about drawing into them and them being dead in your hand, as well as letting you run 1-ofs for niche or situational plays and not worrying about them taking up room. The down side to this, though, is that most of your main deck is going to be composed of fodder for your Chimera, so were Lilias to die or your Chimeras be made obsolete (*cough* Charlotte's Bear Magic *cough*), your deck won't be able to function well on its own. Building him means you'll need some strong main-decked win conditions such as the Riza-Melder Stealth combo. Lilias' absolute biggest weakness, though, is the fact that you have to have Killing Stone to do anything, and there are very few ways to get it out of the stone deck aside from praying to RNGesus.
Being Black/Green, though, puts Lilias in the perfect position for this play style. He has most of the negation, ramp, and destruction in the game available to him due to his colors, letting him take on a much more control-heavy play style and baiting/negating any answers the opponent may have to his large creatures, then cheesing them in for cheap and bashing face. The three Chimeras he currently has give him resonator spot-removal, hand control, Addition/regalia destruction, and massive ramp, all at the drop of a hat.
Honestly, Lumia is the Ruler I've paid the least attention to this spoiler season, although she's likely got the most potential out of any of these new cards. She's a Light/Fire card, which are the two weakest colors at the moment, so her pool of tools is pretty limited compared to what everyone else has to work with. A strong Lumia deck will likely be 3-colored, but keeping strictly to her two colors isn't impossible, given the neat tools she got in this set. You can theoretically run any combination of colors with her, as long as there are strong "When this card enters your field" effects you can abuse.
Her J-Ruler "as you enter" effect is incredibly powerful too. Removing a Nyarlathotep gives her Imperishable and a Lifelink effect, and due to the way Rulers work with the new rulings combined with the wording of her effect, she'll keep that effect no matter what. She died? She'll re-flip with the Imperishable and Lifelink, even if you don't remove another Nyarla. That alone is pretty powerful, since aside from Deathscythe, there's no way to truly get rid of her.
Most of her support isn't anything to bat an eye at. You have Blessed Knight which is a vastly over-costed 4/4, but becomes spammable removal when combined with Lumia's blink effects. Fairy of Recurrence is a flying chump blocker that you can abuse for +2 or +3. Nyarlathotep herself is an incredible card, giving you a huge swing in momentum, and the Red/Light Pact Spell is a Pot of Greed with burn/life gain.
Just looking at this set, Lumia really got the short end of the stick support-wise. However, the sky's the limit when it comes to her actual usefulness since she works with virtually any color that has an effect she can abuse. As we get more effects like that, she only grows in utility. Lumia is one of those cards that might not be immediately good, but she's just waiting for that one card (or for someone to find that one combo) to break her and make her Tier 0.
Rounding out the lineup we have
Mercurius Mars Sol. This guy basically made Mars obsolete, and Mercurius is only really still relevant because she has Flying. Sol has innate access to every Ancient Magic in the game (aside from the 2 Darkness ones), meaning he can play Mars' or Mercurius' decks exactly the same they can, but can naturally splash the other's colors, not to mention all the Red/Blue spells we got in this set. Rune of Sol searches any Ancient Magic, Sympathy of Fire and Water gives him speedy ramp without needing to flip, and Steam Explosion, in combination with Volga, can OTK the opponent with only the Mana counters you get from starting the game and Judgmenting.
Ancient Barrier is another strong support card this guy got, which severely hampers any deck except his own. Good luck cancelling his spells when you have to pay double the will to do it. At least his familiar, Akiot doesn't have the utility that the other two Familiars have. That, combined with Sol not gaining a keyword and coming in as a 500/500 unless you remove Akiot, at least helps to make Mars and Mercurius look enticing. The sheer amount of flexibility this guy has with his play style will definitely let him see play. At the absolute worst, he's Mercurius that can search Rising from the Depths without having to splash colors. At best, he can run 1 of every Ancient Magic and search whatever he needs/wants for the situation. A good Sol player, with a well-built Sol deck, will easily have 2-3 different win conditions in his deck that you'll be forced to play around simultaneously.