The sword really shouldn't have made a difference.
He was Superman. If you shrunk down a bomb, stuffed it up his nose and then set it off, you'd be lucky to make him sneeze. Something as basic and primitive as a sword should have been nothing to him.
However, two major things conspired to make this not true.
First was the man wielding it. "Uncultured barbarian" or not, He-Man was keeping up with both his strength and speed. About the only physical advantage Superman had is that He-Man didn't seem to be able to fly, and that wasn't helpful right now. In the air he'd be a prime target for his mage buddy, even with Zatanna keeping him distracted.
The second was that the sword appeared to be magic, one of the things that completely bypassed his invincibility. The only reason Superman hadn't lost a hand finding this out was He-Man's tendency to strike with the flat of the blade, not the edge. In addition to being able to cut him, it also seemed to be indestructible, as He-Man was using it to block all of his punches without issue.
He opponent grimaced. "Where did you get such power, Skeletor?!" He quickly jumped back out of immediate punching range and swung his Power Sword out at Superman as he tried to close back in. "I swear that I have never been pressed by you this hard, and yet… memories stir at the back of my mind…"
Superman grimaced right back. He'd fought enough magical, time-travelling, reality-warping, cosmic and/or divine enemies that his timeline more closely resembled a bundle of crushed tumbleweed then it did a linear progression. It was entirely possible he had fought this man before, multiple times even, only for the fights to un-happen.
Superman flew in a tight circle around He-Man, quickly building up tornado-force winds. He-Man's feet briefly left the ground before he stabbed his sword into it to anchor himself. That tied down his hands, however, preventing him from dodging or blocking a flurry of punches from Superman to his chest. He-Man's mouth twisted as he bit back a cry of pain.
The assorted cannons placed around Castle Greyskull moved in concert to target Legend as best they could, though they were not built to hit such a mobile target as he, and shot past him into the sky. Legend's own retaliatory lasers splashed against the forcefield, causing it to glow a bright yellow colour but nothing beyond that. Both Legend and Man-At-Arms grunted in frustration.
Zatanna, on the other hand, wasn't doing that badly. Orko showed no signs of moving out from behind the forcefield, but he didn't seem to be paying her much attention at all. Sure, he sent the occasional beam of purple magic in her general direction, but his primary focus seemed to be the He-Man/Superman brawl.
Whoever had set this shield up had access to far more magical power than she did, and they seemed to know at least basic dimensional mechanics because she hadn't been able to teleport or phase through it.
However, air did seem to pass through it, if the gentle breeze coming though the shield was any indication. Presumably, those inside wished to keep breathing through a protracted siege. Zatanna shrugged. Their loss.
Zatanna raised her wand high, aiming it at Orko. "Wolb mih ot em!"
Orko squawked as a sudden gale-force wind blew him clean off the battlements and sent him sailing through the air to land, face in the dirt, at Zatanna's feet.
"Sure, Weather Wizard might be sending me a Cease and Desist when he finds out…"
Orko lifted his head off the ground to find the tip of Zatanna's wand an inch from his nose.
"…but right now, you're out."
To her surprise, Orko actually snarled at her. With surprising speed, his staff went up and knocked her wand hand aside, putting her off balance for just long enough for him to cast one more spell. Another purple beam shot out of his staff, slamming into the back of Superman and causing him to howl in pain, a purple aura starting to glow from his body.
Now that she was within a metre of the casting, Zatanna was able to sense something she hadn't from so far away – Orko's magic actually felt distinctly evil.
He-Man took advantage of Superman's distraction to pull the Power Sword out of the ground and lift it into a guard position (the winds having died down), but he didn't attack with it, instead just watching Superman writhe in pain in confusion.
Zatanna cast her next spell on a hunch, grabbing Orko by the front of his robes and hoisting him up so that his face was level with hers. "Wohs em ohw uoy yllaer era!"
With a snap, the image of Orko the diminutive mage broke in half, revealing the creature who actually looked rather similar to He-Man, only he was purple and had a skull for a head.
"Skeletor?!" He-Man and Man-At-Arms yelled in surprised unison, the latter ceasing to fire.
"Eh," Skeletor shrugged, speaking in the same nasally voice that Superman had been speaking in earlier, "I was getting tired of pretending to be that idiot anyway."
He-Man's face twisted in fury. "What have you done with the real Orko, Skeletor?!"
"I wouldn't worry about him if I were you, you babbling, bumbling, blundering baboon." Skeletor pointed up at Superman. "After all, my curse should be done about now!"
With a howl of pain, Superman split into two – one red, and one blue.
The blue Superman dropped to the ground, exhausted.
The red Superman gave an evil grin.
Angle Island, as it turned out, was an utterly impossible patch of real estate – a literal island floating in the sky. Boarding it required utilising an ancient teleportation device that came out in a series of ruins.
"Geez, you live here?" Joseph Joestar shaded his eyes with a hand. Nothing but crumbling stonework as far as the eye could see. "Why don't you move somewhere more cheery? You know, like a morgue."
"Are you done?" Knuckles growled.
Batman, meanwhile, was examining the flora growing underfoot. "You live here alone?"
"For as long as I can remember, yeah." Knuckles shrugged, not seeming to think much of it.
"Hm." Batman grunted, eyeing the thoroughly trampled grass suspiciously. "Take us to the emerald."
'Altar Emerald' was another ten minute walk from the teleporter. Knuckles seemed unconcerned about the unstable bridges and hole-ridden ceilings, though considering that he was strong enough to lift and throw boulders, he might not have considered a wall falling on him a real problem.
The Altar sat in the middle of a grassy field, two levels of stone with a staircase leading up to where the Master Emerald was supposed to sit.
Was supposed to.
"NOT AGAIN!" Knuckles roared, running up the stairs to the altar at what was actually a pretty impressive clip, reaching the top of the altar within seconds. "EVERY TIME, I SWEAR…!"
He furiously picked something up from the depression where the enormous jewel normally sat. "What? An envelope?!" He tore the paper open, leading the very brief letter aloud. "Second of the second, slightly to the left of the first?!"
{First this Jewelled Sceptre, now a Master Emerald… both times, clues left behind…} Kumagawa pondered, rubbing his chin. Then he smiled brightly, holding up a finger. {We're dealing with a real moron here!}
"Hey, Man-Bat!" Knuckles yelled, jumping down from the altar. "You figured out Blaze's riddle pretty quick – where's the guy who stole the Master Emerald?"
"You won't have to look far." Batman said, choosing to let the mangling of his name slide. "We must have surprised them, coming back when we did – they haven't left the island yet."
"They haven't?" Knuckles repeated blankly. Then he caught his fist in his other hand. "Oh, right! The island hasn't fallen out of the sky yet!"
"That's a thing that can happen?!" Joseph yelped, jumping up and balancing on one foot, his triceps bulging out of pure habit as he held his arms up to his sides.
Batman blinked slowly, processing this information. "That's… not what I meant. These ruins were built by your people, were they not?"
"They were built by echidnas, yeah."
"And no other people lived here? Definitely nobody like us?"
"No overlanders lived up here, no. Look, do you have a point?"
"So why's that doorway over there twice as tall as all the other ones?"
Even as those assembled turned to look, there was a sharp click, and the three humans and the echidna suddenly found themselves frozen in place, their legs freezing in place.
"Looks like you're just as good of a detective as they say you are."
Joseph perked up in surprise. "That voice…! No, it couldn't be…! It's not possible!"
The pile of crumbling stone that Batman had pointed out (and, Knuckles suddenly realised, lay in the direction that he could sense the Master Emerald in) suddenly exploded outward, revealed for what it was – hasty camouflage. The 'door' Batman had noticed was instead revealed to be an entry hatch for some kind of VTOL aircraft, and striding out of it…
"Don't bother trying to move." The woman said, adjusting her fedora. "I've stolen your ability to walk." Her right fist was clenched tight around something the others couldn't see, and she quickly tucked it into a breast pocket.
Behind her came a group of obvious thugs, brutes with dim eyes and biceps that could actually give Joseph a run for his money. They fanned out behind Batman and the others, grabbing their arms and wrenching them behind their backs. Six of them were needed to hold Knuckles, even though he had no leverage.
"Long time, no see, Joseph." The woman said, a simple wooden cane dangling from her left arm.
Joseph grimaced in reply. "And just where in the world have you been, Carmen Santiago?!"
Flash had been in the Superhero business for long enough to know that when the obvious bad guy's doohickey started to glow, you didn't just sit around like a sack of potatoes. In less than an eye-blink he was across the room, punching Thanos as hard as he could in the inside of his elbow. In pain, the titan unclenched his fist. Flash eagerly reached up to grab the gauntlet off his massive hand and –
To those whose perception didn't operate at speedster levels, the Infinity Gauntlet seemed to suddenly explode in a massive flash of lightning, throwing Flash away (wait when did he get close to Thanos?) into the wall with a loud BANG.
"You're fast, aren't you?" Thanos chuckled. "Too bad taking this off me is going to be harder than you'd think." He pointed his gauntlet at Flash, the green stone now glowing. "Now stay –"
His teeth were suddenly grit as he found himself sharing his head with an angry martian.
"Go!" Manhunter roared, both verbally and telepathically.
Ant-Man didn't need any prompting, having already run half-way across the room at a centimetre high. Skidding to a halt underneath Thanos, Ant-Man suddenly surged in size, his fist upraised to punch Thanos's jaw on his way up. Stopping just short of the high ceiling in height, nearly twice as tall as Thanos, Ant-Man went to kick him off his throne completely.
The third stone on the gauntlet – the yellow Mind stone – glowed for just a moment, and Manhunter's look of concentration was replaced with a roar of pain, his features actually melting a little as he lost control over his shapeshifting.
Given a moments reprieve, Thanos pressed a button on the arm of his throne, and from the top of the throne shot a beam of energy into Ant-Man's chest, blasting him back into Manhunter and Mr Fantastic. Flash jumped to his feet, but then the green Time stone glowed and the Flash was suddenly frozen in mid air.
"No games." Thanos rumbled, standing up from his throne.
Mr Fantastic eyes frantically switched their gaze between Thanos and the Flash. "If you guys distract Thanos for a moment, I think I can free him!"
I will… need a moment. The Martian Manhunter projected, phasing down through the floor.
Ant-Man gingerly got to his feet, trying not to step on either Mr Fantastic or the time-stopped area. "Guess it's up to me then."
"Fools."
Ant-Man screamed as Thanos lifted the Gauntlet again, the Power Stone glowing brightly and projecting a huge line of electricity into the hero.
"You really are all dancing on her strings, aren't you?" The Titan muttered.
Mr Fantastic, who had been quietly stretching his way around to behind Thanos, suddenly paused. "Wait, what?"
With a roar, Ant-Man swung his fist down onto an unworried Thanos…