Should Elise be retconned? (it's pretty big, huh?)
TL;DR: it's a fucking wall of text where I talk about a champion no one cares about. https://i.imgur.com/6xCISRk.jpg
With the release of Vlad's new lore, Noxus has finally become oversaturated with villainous immortal magic users and, unfortunately for her, that's exactly what Elise is. In fact, that's the entirety of her character.
The problem arises, however, not from any of Vlad's lore, LeBlanc's, or Mordekaiser's; rather, it's Elise who is the least relevant character of that type currently associated with the faction.
In the old lore, the character archetype of "immortal cult leader" was generally limited to Elise. Characters who came before her played with the trope, but never went too much into detail and set foot on her territory. However, with the lore reworks of Vladimir, LeBlanc, Mordekaiser, Evelynn and likely several others, that territory has become a bit too explored - at least as far as Noxus is concerned.
Indeed, not only is Elise irrelevant in the overarching storyline of Noxus, she's absent from it entirely; like Vladimir says, he and LeBlanc are the ones dancing in the blood that others have spilled for their sake. They're the true leaders of the Black Rose, and everyone else is just a pretender - puppets being pulled by their strings.
This isn't what Elise's character is about, though. By no means is she a master of the arcane or an super-intelligent genius, but she's the one pulling others' strings; her personality revolves around her ability to manipulate the weak-willed into doing her bidding, as she is a social expert of unparalleled prowess.
Therefore, to have her reduced to less than even a footnote or mention in the Noxian lore makes her feel like a useless character. Her lore portrays her as someone pathetic: she was groomed by LeBlanc for her role, met Vilemaw by chance, and is now completely dependent on the patronage of the pale sorceress. This is a powerful woman? A regal, vampy seductress? She sounds like an ugly pet kept around by her betters for their amusement.
She's not necessary in the Noxian story. This is further proven by the fact that she's categorized as a Shadow Isles champion. And she's not needed in the Black Rose, either.
So, what to do?
The easiest solution would be, of course, to completely retcon her character and every trope she's supposed to cover. I won't go into detail why this is somewhat insulting to anyone even barely interested in the champion (such as yours truly), or any champion for that matter, so I'd like to propose an alternative. Two of them, in fact.
In my opinion, Elise's character is best summarized in the following eight words: immortal, shapeshifter, terrifying, regal, beautiful, selfish, inhuman, ravenous.
Obviously, these words don't make the most unique, inspired character. She's a pretty cliché example of Evil is Sexy; a deadly seductress who lures the noble hero into letting his guard down before killing him for her own purposes. The trope is already covered by characters like Ahri, Cassiopeia, Evelynn, Morgana etc. The main difference between them and Elise is in how Elise can be handled.
Befitting of the title of "Spider Queen", what can differentiate Elise from her sexy, evil peers is her general demeanor: Morgana is sexy, but not an evil seductress; Ahri, Cassiopeia and LeBlanc are playfully manipulative; Evelynn is a naughty, bloodthirsty demon. Unlike them, Elise gives off a regal, refined air, and pretends to be comforting (maybe even motherly?) to her followers. Her VO can reflect this: her lines could be serene and eloquent - she's in no rush to kill you. Every word is a venomous, veiled threat, but is spoken so sweetly you'd imagine it was a compliment.
Speaking of "two solutions", I've decided to create two, not-so-fresh takes on the character in an effort to breathe life into her - she's pretty stangant and lifeless otherwise, though that is her theme.
The two themes I've chosen are as follows: evil queen and lovecraftian cultist. I'd call the names works in progress, but I'm too lazy to come up with something more original later.
#EVIL QUEEN (bonus points for referring to Vilemaw as "God") https://screenbeauty.com/image/wallpapers/stones-wood-dark-135223.jpg
She isn't really a nice person, is she?
Elise1 is Elise as an evil queen from a fairy tale: the ruler of a fallen nation who's out to restore herself to glory. This nation can be anything: maybe it was a small kingdom on the Blessed Isles overthrown by the resident magical society because she was a black-hearted tyrant who desired their knowledge over life and death; maybe she's the ancestor of the Ruined King, who has schemed her return through Hecarim's betrayal and the release of the Ruination. The point is, she's an evil queen with a fixation on beauty.
Let's call this "the Elizabeth Bathory": she's basically the eponymous antagonist from Snow White on steroids. She lives in a dark, ruined castle in the middle of the woods (on the Shadow Isles?), and sends out "emissaries" - swarms of spiders enchanted to look like human agents - to guide villagers to her demesne (on the Shadow Isles?), where she ensnares them for all eternity. She wishes to be revered at all times, and works to preserve her looks. She's not so much seductive as she is obsessed with her physical appearance in a non-sexual way.
This could also give her a fairy tale twist: maybe she resembles a fae being, an Unseelie Court-like creature, with a complete disregard for human life. Maybe she contacted Vilemaw - a twisted, aberramt demigod - for the sake of eternal youth? Whatever the case, she definitely likes mirrors and plays up the uncanny valley effect for all it's worth; she's not just pretty, she's beautiful in an inhuman way.
It's quite possible that she stands with, or against, the Ruined King and Mordekaiser. If she allies with them, she might try to pull a lady MacBeth; she's not a black widow for nothing. No links to the Black Rose, though (unless Vlad stole nightblooms from her garden?).
#LOVECRAFTIAN CULTIST (with strange aeons, even death may die) https://www.literacywagoll.com/uploads/3/1/3/1/31318533/39492068-spooky-forest-wallpapers_orig.jpg
Get it? Because she's immortal.
This is Elise2, the insane worshipper of a Great Old One: an eldritch abomination that feeds on living beings and deals in nightmares and madness. Except, she's not an insane priestess and he's not a real god. This is Elise as the "immortal shapeshifter" - an inhuman creature that had, in millenia past, struck a pact with Vilemaw in exchange for eternal youth and power, and now brainwashes thousands of humans to do her bidding, both she and her god hungry for their deaths. Her supernatural form may include spectacular abilities: extending, diamond-tough spider limbs, enhanced strength, speed and perception, the ability to dissolve into and regrow from swarms of spiders; everything fitting for a lovecraftian supervillain.
This emphasizes the most monstrous aspects of the vampire. It's a blend of gothic and cosmic horror, and adds a new, terrifying villain to the world. Think of her as an inverted version of Illaoi: where Illaoi promotes life, change and survival, Elise promotes eternal life, unchanging and the sacrifice of others. She dabbles in secrets and dreams; mad visions spun by her god to infest the waking world with his hunger. Vilemaw, too, is the shadow archetype of Nagakabouros; together, they bring another layer of cosmicism into the universe without being linked to Targon and the Void. If you give her powers of seduction, things could get squicky pretty soon.
She is less likely to ally with the Ruined King and Mordekaiser, and might seek to turn the Shadow Isles into her own realm. Perhaps the Ruination was Vilemaw's doing? Call him "the Spinner in Darkness" and be done with it.
And that's about it. Honestly, I wouldn't mind her story going in either of these two ways, so long as those words I mentioned earlier are preserved in some capacity.
Interacting with Noxian champions obviously isn't her forte, so it would be interesting to see what she could have to say to someone like Karthus or Yorick. God knows she's a pretty insignificant character right now.