I think it needs to be punchier. The effect you're going for is his heart hammering so hard the blood is throbbing in his ears, and the audience can feel that because we're riding along in his skull.
So there are a couple sentences that distract from the core mission of piling on stress.
Like let's take that first paragraph:
dat first paragraph said:
He burned inside and out. With no one to burden him the green-clad druid dashed through the grassland as fast as his legs could carry while the spell lasted, panting as his lungs tried to suck in enough of the chilled air to keep up with the demands of his body. He was so close that he could feel the moisture now lacing the air, a clear sign there was a source of water nearby.
You're going in a couple directions here:
1) He "burned inside and out"; you're pretty good on the "inside" bit, but regarding outside, the only you tell us it's getting wetter, which is like the opposite of "burning".
2) It's strange to bounce from telling us he's burning inside, to looking at him from the outside ("green-clad druid"), and then going back inside his head and looking at his thoughts.
3) Giving us an environmental report about what he could feel outside him is the opposite of telling us what's going on inside him. Maybe make it something about tasting it, or that the cool, moist air was easier on his throbbing lungs.
Vs Kobold said:
It swung its weapon. He dodged it sloppily and then righted himself enough so that the <Shield Bash> it tried to do missed. He grabbed its helmet, drew its head back, and plunged the knife into its throat and violently tore it out in a way that would have been fatal to any living thing. It only registered as critical damage, but that wasn’t really his concern. What was his concern was that it now happened to be immobilized.
Since it's paralyzed because he literally stabbed it in the throat, that statement feels weirdly passive; "happen" implies exterior agency, and the complexity means by the time the reader figures out what it says, the impact has worn off. (I
think that sentence has a present participle phrase renaming the object of the independent clause, which is simple-past tense with passive voice, but there might be other readings of the logic).
Plus since the whole point is that he wants to kill it ASAP, the question of whether critical damage was instantly fatal or not is 100% his concern. It is his in fact his most immediate concern, right?
Vs Kobold remixed said:
He grabbed its helmet, drew its head back, and plunged the knife into its throat and violently tore it out in a way that would have been fatal to any living thing. Unfortunately, for this virtual avatar, it only registered as critical damage. But he wasn't concerned: now it was immobilized.
Then go on to talk about poison. Also I think rather than calmly dropping it, he should savagely and repeatedly be stabbing it in the throat over and over again while going over his preparations, and then he's a little surprised when it disappears; he'd completely lost track of the HP bar while stabbing. (Maybe: Also he realized he had been screaming. That line might be too much though.)
back-up knife said:
He’d resorted to keeping the knife on-hand after applying paralysis poison to the blade.
You're not quite clear on why it's something he "resorted" to. Is it a back-up for when he can't engage at range? It seems like a digression to imply something about "resorting", like you're signaling I should remember it, because you're going to come back to it.
He staggered as he felt his legs begin to ache, the spell wearing off as the [Reinforcement] once more began to falter.
Shouldn't his legs already be aching? Especially if he's faltering "once more"? Or is it that, suddenly his thighs seized up because the spell ended, and it wasn't suppressing the cramping any more?
internal conflict said:
You’re pushing the blame onto others, a small part of him whispered in the confines of his mind. Never your fault is it?
This is getting too introspective; that is, rather than just getting squeezed by pressure, he starts thinking questions and answers about the situation rather than reacting somewhat blindly. (Also the "confines of his mind" is implicit in "small part of him whispered", so it's over-specific; that can be fine, but you're pounding a drum here, so don't go too long between beats).
My advice: drop the question at the end, and have him lead into a monologue that's only
implicitly resentful, while also being him preparing himself mentally to just abandon the other girl (which is in-character for him as a planning-type...).
maybe a tighter approach said:
You’re pushing the blame onto others, a small part of him whispered.
Sympathy? Empathy? Those were things he couldn’t spare while they were trapped in this nightmare. That was why he wanted his brother to stay in the damn city. Sticking to [Safe Zones] and following routines was what kept them alive until now. Survival was what mattered: not the quality of the life they lived, or things like researching new spells, or exploring the world, or any of that.
If that girl died, it would be her fault for endangering herself. He, a stranger, was blameless. Honestly, since it had endangered his brother as well, it wasn't like he was willing to offer her the benefit of the doubt. He wasn't that generous.
Like he told that other girl before, he didn’t ask to enter the game either. He didn’t ask to be made his brother’s keeper. He was only in the game because his parents had promised him concessions for looking after him for an hour or two as he played the game.
Also, I turned one of your compound sentences into multiple sentences, 'cuz that's punchier.