Crawler tore away at the metallic barrier between him and his prize. Officially, it was rated for withstanding an Endbringer attack, but that was a far cry from resisting an actual Endbringer. At the end of the day, it wasn't even Tinkertech, it was merely normal (albeit well-designed) architecture built with normal (albeit albeit extremely strong) materials. He spat a glob of acid onto the entrance and dug in with his hands/paws and nails/claws. Under the effects of his spittle, even the toughest standard materials became as easy to reshape as putty, and he scooped it up out of his way with little care for how it should be burning him.
He'd developed nigh-immunity to his own fluids approximately five minutes after he'd developed acid spit in the first place. Truth be told, that several minutes was so juicily painful he could scarcely even remember what awful thing had happened to him first that acid spit had qualified as a defensive mutation. He remembered being tickled pink about it at the time, because of course he'd been in the middle of a fight when this happened. What little they'd done to hurt him instead made him stronger, and then he'd given them a good licking too. Ah, good times.
He was perhaps halfway through the outer shell of the shelter when his various senses perked up all of a sudden. Someone was approaching him! The street had long since cleared of stragglers who posed no threat and stood no chance, but now some chick in silver armor was approaching without a care in the world. He whirled around. "And what canyoudo to me?" he asked hungrily.
"Less than you'd like, and more than you deserve," she replied haughtily.
Beneath her confidence, he could sense the faintest whiffs of trepidation; whatever she had in mind, she had doubts it would work...which probably meant Crawler could survive it at least once, and that was enough for him. He shifted his weight and charged her down, far faster than any creature of flesh and blood his size should be capable of. The only thing faster was the glob he spat ahead of himself.
And yet, it seemed she'd been ready for just that response. She raised a hand and it glowed with power. "Mutationem planum: Hades~"
His momentum carried him forward, slamming straight into her hand-
-and quite suddenly, he was somewhere else entirely. Crawler glanced around, senses straining to take in everything around him. There was no sign of the woman - indeed, no sign of any living creature other than himself. There weren't any heat trails to go off either, infrared and ultraviolet weren't giving him anything to work with. There was nothing to see, nothing to hear. Nothing but gloomy grey fog as far as the eye could see, no matter which eyes he used. That's not to say there was nothing, though. There was a rotten smell to this place - in some ways, like corpses left out in the swamp, but in other ways, like people dying in their beds of disease or old age. There was no great fight to be had here.
He flinched. Something had bit him. And it had hurt!
Crawler's senses flared once more, straining to detect the source of the issue, but there was nothing around except him. Stranger, perhaps? He spun in place, lashing out with claws and acid. "Face me, coward!" he screamed to the sky, his voice a low rumble.
Another bite, this one harder than before. It wasn't a single wound, he realized, but hundreds of little pinpricks all over his body. He'd been feeling them ever since he first arrived, but it was only now that they had gotten so bad he'd begun to notice. Worse, as he stared at his own flesh, he could see his regeneration was failing him - it wasn't gone completely, but the wounds inflicted on him by whatever this place was were healing far slower than they had any right to.
Another wave of pinpricks, this one painful enough to elicit a yelp.
Had he a need to breath, his breath would've hitched in his throat. It wasn't just his regeneration. He wasn't adapting to it. Or at the very least, he wasn't adapting fast enough to make a difference. Whatever was killing him, it was ramping up faster than his resistances could build.
Crawler broke out into a run, even as another wave of little pinpricks tried to bring him to his many knees. He ran and ran and ran, trying to outrun whatever it was that had been attacking him that he couldn't see, but they followed him step for step. Every several steps, he thought he saw a face staring up at him from the ground - from what he realized was piles of ash as far as the eye could see.
He didn't even make it a quarter mile before he collapsed, lungs heaving from the effort to keep him going. By all rights, he should be able to run all day; even if his lungs were fully removed from his body and prevented from regrowing, most of his other internal organs could take up the slack just fine. But as the bites grew from pinpricks to spears of overwhelming pain, he realized he could feel them inside him as well. Every bit of his flesh was being attacked at the molecular level.
Another wave hit him, and he knew no more.
Shadowheart shook herself off following the little impromptu rainstorm she'd summoned to clean off the acid. Her hand barely shook as she applied restorative magic to her wounds - it hurt quite a lot, but she'd faced worse from the acidic grease monsters lurking in the city sewers. And of course, she thought as a spike of pinpricks went over her body emanating from the spot on her hand, pain was an old friend.