It would be the Zerg.
We can see that Warcraft has powerful magic, but not so powerful that it surpasses steal age tech. The Zerg just do that.
On the other hand if we went by the rules of wc3 vs SC2 then the undead would win. Over 400 hp and almost 30 damage in the most basic unit. A ling is like 35/5 I think?
But if we went by in game , i know this is hypothetical , wouldnt the zerg mess them up severly with just a bunch of mutalisks?
Could we also had lurkers in there too ? Not sure if the sourge has anything to reveal.
Arthas will piss on all zergs with only one swing of Froustmorne.He will rise Sindragosa and have a snack of those pesky zergs.Then he will make Kerrigan his slave just for fun.
The thing i love with this game is that you see fenix , the pinnacle of technology get curb stomped by a caveman wearing fur who disregards his highly advanced defense system by throwing something to his face very hard.
That was literally the only thing Shades could do, wasn’t it?
OT: I think the Zerg would win easy, beacause of something not mentioned here yet:
The Scourge was defeated, repeatedly, by Horde and Alliance forces, right?
Well, the Zerg infest all of Azeroth, including the Horde and the Alliance, in a couple days, then used those infested magic-users to stomp the Scourge!
The Plague of Undead from Warcraft 3 got nothing on the Zombie-Apocalypse-inducing version of the infesteation that we see in Starcraft 2. (compare Arthas “purging” the whole city of Stratholme vs Selendis wanting to “purify” the whole planet of Haven, both for simmilar reasons).
By the way, I’m not sure about this, but I think Kerrigan is a lot more powerful than the Lich King when it comes to psionics
Lich King had to slowly expand his consciousness over Northrend (a single continent) in order to exert control over his subjects (though he was just learning his powers, so he could probably be stronger “now”).
Also, the Forsaken broke free of that control just because they had strong willpower or something.
Meanwhile, Kerrigan can telepathically comunicate with her broodmothers throughout the entire Koprulu sector, simingly instantaneously (though that might just be how it looks because of “editing”), to have them beat down the Dominion so she could invade Korhal.
And before that, in Broodwar, she psichically controlled Raszagal, who was at the very least a Protoss, and those are known for having very strong Psionic abilities.
So it’s not entirely out of the question that the Queen of Blades could simply steal Arthas’ armies by psionically outpowering him.
Call me a fan boy here but im under the impression that primal zerg kerrigan could just solo through arthas’ army and then kill him shortly after.
Really , if kerrigan trully goes all out , is the zerg army even needed there ?
Mate, Arthas will destroy Kerrigan with a hand behind his back.Hes’s the greatest and most epic character Blizzard ever created and one of the most badass villains of all time!
Character-wise, aren’t Arthas and Kerrigan nearly the exact same? 
I mean, I do find Arthas’ “fall from grace” story more interesting than Kerrigan simply being betrayed, but I feel that that compelling aspect of him got somewhat rendered pointless when they outright “took his soul” with magic after.
Back on the “who would win a fight” side of things, I guess it depends on wether they fight one-on-one, and wether in that fight Arthas can just insta-kill Kerrigan by stealing her souls with his knock-off Soul Reaver
But the discussion was about their armies: the Scourge and the Swarm, and I still think the Swarm wins out.
Then again, I don’t know how much “spectacle creep” WoW went through, so I’m unsure how powerful Death Knights are supposed to be (and I think those are the only thing that might give the Scourge a chance).
Mutalisk have only 100 hp the hero units do over 50. He’ll 1 cast from KTZ kills them all.
Arthas would beat Kerrigan becasue he has HAX in the form of Spirit Based attacks somthing I don’t think anything in Starcraft has to the same degree
The FUry of Forstmourne attack he used to wipe the raid in IceCrown Citadel would one shot Kerrigan then she’d be revived as a master of the Scourge
Then God Help whatever unierse they are in Zerg with the undead properties of the scourge sounds horrifyingly OP even the Hybrids would cower.
However that said if we remove both Arthas and Kerrigan from the equation and compare them as soldiers and armies (removing all their big players, so no Stukov Deahaka but no Kel’thuzad or sindragosa either
Then I could still make a case for the Scourge because even without Arthas they still have a great deal of Hax among their Death Knights and similar, even if the Zerg are immune to ice powers, shadow and more importantly the way blood powers are described it coul tear the zerg apart.
The problem is always going to be magic, magic doesn’t work in the same reference frame as normal physics.
… Only problem is, the Protoss are essentially the same thing. Psionic powers are basically just space wizard magic that don’t work in the same frame of reference as normal physics.
This entire thread looks like something I would find in a fanfiction.
Arthas would be able to deal a lot of damage, but I doubt he’d be able to do much to an Ultralisk or an endless tide of Zerglings and Hydralisks, let alone being bombarded with Broodlings from miles above him by Brood Lords.
If a group of adventurers of Azeroth were able to beat him, there is no way the Zerg would not be able to.
Sindragosa is basically the same thing. Masses of Corruptors and Mutalisks spewing acid and glaive wurms (these little suckers are really nasty) would inevitably wear her down, literally dissolving away at the bones and ligaments holding her together.
As for Kerrigan vs. Arthas, you’d have to be joking. If you are serious, you are vastly underestimating how powerful Kerrigan is.
Kerrigan can physically rip through anything in her path. She can burrow under the ground and fly. She can literally explode your head with a thought, both telepathically and telekinetically. She can crush Thors like tin cans and pull Battlecruisers from orbit with her mind. She can release psionic blasts that rival nuclear explosions.
Short of giving Arthas his oneshot “soul rip” trick and guaranteeing it would work on someone like Kerrigan, Arthas would stand no chance, and even then he’d need to get the drop on her for her to not just kill him outright with telekinesis.
We’re going by canon abilities and capabilities, not gameplay mechanics. Otherwise, Zerg would win basically every game of SC2 if they make it past the early game.
Mutalisks are fairly fragile, but they are also incredibly nimble, very lethal, and they travel in swarms.
I have no doubt that liches would be able to take down quite a few of them, but there is no way they’d be able to stand up to a whole flock.
Would probably be best for the Scourge to not revive her, though.
If Sylvannas could break free of the Lich King’s control, then I’d bet Kerry could do it easily. Then you end up with an angry Undead Queen of Blades 
So I guess in the end it comes down to wether Arthas and Kerrigan are involved, and if so, wether Zerg have souls.
Pft, I killed him with a group of friends wielding pointy sticks.
Repeatedly.
And yet, still no Invincible mount. Sadness.
(OK, OK, lore wise we did have a little help from a Fordring and a magic sword, but still…)
Edit: Doesn’t Frostmourne require a target with a soul to be effective? Do zerg even have Azeroth-style souls?
Given how in Warcraft 3, Arthas would yell “Frostmourne Hungers!” and “You will suffer eternal torment!” at wooden boxes, his sword probably works in soul-less things 
That’s what I said! 
Also, if Diablo can collect souls from Probius and D.Va’s mech (and Butcher collect meat), then -by HotS logic, at least- Arthas can soul-attack Zerg
Anythingwitha concscience has a “Soul” persay, even animals in warcraft have souls,
So I could make a case for yes actually the Zerg would have Azeroth styled souls
Also no that I think about it there is one very major thing to consider
Ho the Zerg virus effects the undead and how the Plague of Undeath effects the zerg.
Oh goodness now that’s a debate that’s quite… appropriate for the times.
I mean, its not like death is permanent for some zerg
The whole discussion about Magic vs Technology is irrelevant. Do you guys know Clarke‘s third law?
Any sufficiently advanced technology is indistinguishable from magic.
Even if the zerg would use (bio)technology the scourge couldn’t distinguish it from magic.
Hm, it depends on the resources the Scourge start with. Once they start killing Zerg, they can resurrect them as undead Zerg under the Lich King’s control, but to do that they first have to kill enough Zerg to make a difference. Skirmishes, ambushes, reanimating as they go. If they can get momentum, the Scourge win a war of attrition. If it’s all about a single battle, then Zerg hands down.
Unless, of course, some magic comes into play to convert a whole army of Zerg at once, such as Sylvanas attempts against the humans in the BfA intro. Then who knows.