How they compare: Jadis the White Witch (The Chronicles of Narnia)

Once there was a world referred to now by it's capital city Charn, much older then either ours or the world of Narnia; it's skies so dark a blue as to be almost black and it's sun massive and red for hundreds of thousands of years, populated by a species of very tall humanoids believed by some to be descended from giants. 

As the Charn royalty degenerated from nobility to savagery, mirroring the degeneration of the world, the world grew closer and closer to civil war. Born last and most intimidating and degenerated of the royalty of Charn was Jadis. While all the nobility of Charn had access to magic, Jadis delved into far darker magic then was considered acceptable, even learning the forbidden magic hidden away by her ancestors "the deplorable word". Jadis and her sister engaged in civil war with each other. While the two had both sworn off the usage of magic according to Jadis, her sister broke the pact first. The armies of Jadis' sister proved stronger and after their final battle her sister said her final word declaring victory when in spite and hatred Jadis used the Deplorable Word destroying her own world.

Jadis alone then masterminded a plan to be eventually freed from the dead world of Charn and find another world to conquer over. She would find her way to Narnia and become the infamous White Witch, she who would mastermind rebellion in Narnia against Aslan.

Befitting her large stature as a native of Charn, Jadis has physical capacities beyond what a human from Earth might be capable off.

Jadis is strong enough that she could easily break the bones or kill a human and in the brief period she was on Earth she demonstrated that she could "break an iron bar as easily as barely sugar" and easily snapped off part of an iron lamppost. This would take energy in the ranges of thousands to millions of joules, which is wall level.

Her durability is similar as she has fought against and survived the blows of beings that were her equals including her sister in the civil war and Peter Pevensie, the future King Peter, in the war for Narnia.

In terms of speed, Jadis is fast enough to move that during her fight with Peter Pevensie it appeared that the one blade she wielded was actually three blades to onlookers, showing she was creating afterimages with her speed, requiring subsonic speed.

Jadis as a skilled magic-user, has a varied arsenal of magic abilities. She famously was able to trap the nation of Narnia in eternal winter, covering it in snow for 100 years as she ruled it. This was not a normal winter either, it was a winter where it was never Christmas. This was not a fancy was of saying she royally kept it from being Christmas, she was able to magically bar Father Christmas from coming to the world of Narnia. This suggests she has planetary scale wards (a ward being the opposite of a seal, keeping characters from entering as opposed to keeping them from leaving like a seal)

While she was in Charn she was able to cause giant palace door to turns to dust. Conversely, she can also create from nothing, as she created food and drink that was actually enchanted to cause whoever consumed it to become obsessively addicted to consume even if it killed them. Speaking of mental affects, Jadis has the ability to passive hear the thoughts of others and was able to create an illusion to disguise herself and her dwarf servant as a boulder and a stump.

Jadis also has numerous ways of ceasing motion. She was able to turn her enemies to stone, even numerous at once (such as turning a gathering of people to stone). She was also able to put herself in suspended animation, freezing herself in time, for 1,000 years until someone entered Charn so she could escape from the dying world.

Witches are also known for their immorality, such that even if they are killed their "essence" (likely spirit) remain and linger around rather then going to Tash's country such that they would surely go. While this is obviously a highly reduced state, it is also possible for them to manipulate others into resurrecting them once more. This aids her ageless immortality gained by biting the silver apple of life

However Jadis has one more spell, her most infamous spell, the accursed Deplorable Word, a word that killed every single living thing in all of Charn. "Worlds" in Narnia seem to be able to be applied to either planets or universes, so this should be seen as planetary, possibly universal death hax. This was so powerful that once Jadis left Charn, the world itself dried up and disappeared from the wood between the worlds.

Jadis besides her magic is also a skilled melee fighter to the point of equaling a skilled swordsman with just her stone knife, as well as veteran commander of the Charn civil wars. She is also a skilled manipulator being famously a temptress aided by her "hypnotic" beauty.

In terms of weaknesses, Jadis is vain, arrogant and easily enraged as well as afraid of Aslan. In addition she is reliant on her wand to cast her spells, her magic seems to depend on the world she is in, as she was unable to her use her magic properly while on Earth, and it's implied the Deplorable Word takes a bit of prep requiring the "right ceremonies".

Name: Jadis, The White Witch, Empress of Charn, Queen of Queen and Terror of Charn
Origin: The Chronicles of Narnia
Classification: Witch, Potentially giant-blooded royal of Charn
Powers and Abilities: Superhuman physical capacity, agelessness, country scale snow manipulation (covered Narnia in Winter for 100 years), planetary possibly universal warding (kept Father Christmas from entering Narnia for 100 years), can persist as just an essence, can freeze individuals in time (as she did to herself), petrification (numerous people), illusions, creation (can create enchanted food and drink that mindhaxes opponents into obsession), transmutation (turned giant palace doors to dust), death manipulation (planetary, possibly universal)
Weaknesses: Vain, arrogant, easily enraged, afraid of Aslan. Reliant on wand and magic in the world to cast spells. Deplorable Word may require prep time.
Destructive Capacity: Wall Level physically (snapped iron as though it were sugar), higher with magic
Range: Planetary, possibly universal
Speed: Subsonic (Moved fast enough that she seemed to be wielding 3 blades, instead of one blade)
Durability: Wall Level (survived blows from her physical equals)
Stamina: Massively superhuman (Maintained her magic for a century)
Intelligence: Clever (manipulative and a skilled fighter)

So how would she do in other verses?

In the Marvel Universe, Jadis could hypothetically be much stronger since her magic is dependent on the world she's in and the Marvel Universe has lots and lots of magic in it to the point it's called "universal energies". That said it's speculation so this is just how strong she would be normally.

Physically speaking Jadis is basically human level, as Marvel Street Levels regularly scale to feats massively above what she has displayed.

That said her magic would be incredibly dangerous. Her ability to create eternal winter and ward off entities would be hard for the verse to get through without getting into herald or higher level entities. And the Deplorable Word, from what I know, would absolutely wreck the universe if she got it off. It would be like if Thanos snapped twice. You could argue beings that can't die such as robots like Vision or undead like the vampires Blade regularly fights wouldn't be affected but given that the Deplorable Word caused the world of Charn itself to die I am not sure I would agree with this assessment. I don't even think most Herald Tiers could survive the Deplorable Word. The best case scenario is that one of the marvel telepaths or sorcerers notices the threat and stops her before she completes it. 

I'm just gonna come out and say it, I don't think I've ever seen a character so uniquely unsuited to fight a verse then Jadis in DC. First of all while Jadis might be stronger in DC for same reason as Marvel, it's also possible she could have literally no magic like Narnia-verse Earth because DC magic is as far as I know always stated to reside within a person (like the Homo Magi) or within an object (like the Helm of Fate) or to be derived from other realms like the shadowlands and magic doesn't just exist everywhere. I do think Jadis would be a bit more of a physical threat in DC then she would be in Marvel. With her combat tricks like mind-reading, petrification and transmutation, illusions etc. she could probably fight decently against DC characters around the level of strength of average amazons and atlanteans. 

But all of Jadis bigger abilities can be countered pretty confidently. You can persist as a essence? Well guess what the verse magicians love to seal intangible entities away. You can create planetary, possibly universal and possibly conceptual wards? Well how about 7 DC mages being able to seal DREAM OF THE ENDLESS. Oh you can kill everything in a universe except yourself. One of the easiest spells to cast, to the point Superman after temporarily gaining Zatanna was easily able to cast it, returns a magic to it's source or inverting a spell causing it to just kill ya. There's also the fact that speedsters that are fast enough can return a magic to it's caster by spinning or the White Lanterns who reversed the death manipulation of Nekron, Universal Embodiment of Death. Post-Crisis Superman without any of this was attacked by the embodiment of death of an entire universe and punched him in the face. How about the fact that DC mages love to take fighs to other dimensions, you know where Jadis explicitly can't escape from?

Jadis is uniquely UNsuited to fight DC. She'd be a decent fighter with a good variety of abilities against fodder tier fighters but her big abilities are more likely to get her killed by calling the attention of one of the most competitive magic-wielding verses in existence. 

Tolkien and Lewis were good friends and the Chronicles of Narnia are often compared to the Lord of the Rings. In Middle-Earth Jadis would do oddly. Her power would depend on the age she's in, as magic slowly left the world over the ages, but again it's speculative how this would affect her overall power level.

Statwise, Jadis would be above human tier, who only ever get up to somewhat superhuman due to their status. That said she would be a lot weaker in most regards compared to the general wizards and supernatural entities like the Elf Lords given they scale to massive feats she simply can't compare to like splitting the sides of mountains, crumbling fortresses, causing the Earth to shake and whatnot.

She would do pretty interestingly against the Nazgul. Her snow manipulation may trigger their weakness to water but their fear aura may cause her to see visions of Aslan. She likely has higher reaction speed and if she could probably find some way to kill them with her trickery (especially since she can ward against them or suspend them hypothetically in time), though if they do kill her they would be able to hypothetically to permanently kill her as the black breath of the Nazgul drains life-energy and they would be able to see through illusions given their nature as beings existing in the unseen world. Though she would be at least able to know their presence and detect them given her mind-reading.

Beyond all that Jadis warding and eternal winter could cause significant trouble for Middle-Earth, particularly if she knew to bar the access to the Valar and Maiar though it's probably impossible for her to ward off the strongest entities in the universe like Morgoth. Her Deplorable Word would hypothetically kill anyone currently existing in Middle-Earth though the Valar and Maiar would likely reform in their true forms in the timeless halls.

In the Inferno, another old Christian literary verse that associates evil with eternal ice, Jadis would be relatively comparable to the damned who can survive such tortures as boiling blood and would be a little slower given the damned can go to the horizon in the time it takes to say "amen".

Against the damned themselves, Jadis would do interestingly able to potentially counter their ability to see the future, but not the past, with her mind-reading and general intellect. While most of her abilities would not affect the damned given their nature as "shades", the Deplorable Word and her ability to induce suspended animation arguably should. While the monsters of Inferno like the Harpies and the Centaurs are more powerful and versatile then the damned, Jadis powerful abilities like her ability to induce petrification (already noted to be strong in the verse with the Gorgons), her ice manipulation, transmutation, illusions and so forth should give her a strong advantage. She may even be able to defeat the bigger physical threats of the intermediate tier like Geryon or even the giants and Satan if they are trapped via her hax abilities (though if they are free it's possible they could blitz though even then she could ward them off and perform the Deplorable Word)

That said, the ascended made of Actus Purus would be immune to even Jadis' wards and the Deplorable Word and would be so much more powerful, fast and hax that Jadis would have no chance.

Look I know Jadis vs Elsa is a thematic fight, it's a VERY thematic fight, but that doesn't make it fair. 

Elsa can compete with Jadis physically as she can survive wall level attacks from The Nokk and has subsonic reactions from tagging a crossbow bolt in midair. The two have fairly even levels of ice manipulation in terms of scale, with Jadis having maintained it a lot longer while Elsa has more versatility.

But besides that Jadis has a large grab-bag of haxes, including the ability to ward Elsa off and kill everything in the universe. Even if Elsa does manage to get a lucky shot off on Jadis, Jadis can eventually manipulate her own resurrection. 

Not that she's gonna get it. Jadis can read Elsa's mind, create illusions, turn her to stone, turn her to dust, freeze her in time, or just stab her with a weapon being a far superior physical warrior. She has plenty of one-shot options, haxes comically and drastically superior to anything in the verse, and is a better fighter. Elsa at best can summon minions and constructs out of ice that Jadis can casually reduce to dust or stone

Jadis 99/100s with the other 1/100 being Elsa gets a lucky shot in immediately and Jadis has no way to manipulate her way back into being somehow or other. 

This has been why Jadis vs Elsa is not a good matchup idea. Thank you for coming to my TED talk.