Explosions were very cool. That was just a fact of life. They were also, paradoxically, both very hard to make work and also hard to prevent. As he knew from experience, dust explosions could happen at any time when one was working with something flammable. But he was finding out getting explosions to happen consistently was much harder than he had anticipated. Even Bomb Throwing didn’t always cooperate, though he could at least reliably turn it off.

Really, it was just a matter of control. Explosions were in some ways the maximum demonstration of chaos, and it was phenomenally tricky to make chaos do exactly what you wanted it to. It wasn’t even because chaos was some sort of metaphysical force whose bounds transcended mathematics.

No, it was much more sinister than that.

It was statistics.

Simply put, there were very few ways that an undetonated bomb could be put together. Molecules needed to be in the right positions, the detonator needed to be aligned properly, so on and so forth. But a bomb after it had blown up? Well, that had nigh-infinite ways it could exist. That was the secret of entropy, after all. It wasn’t inevitable, it wasn’t some cosmic law that entropy had to increase. It was just overwhelmingly statistically likely due to the fact there were way more ways that an object could be put together incorrectly than the handful of correct states it could exist in instead.

…where was he? Oh yes, explosions.

Another complicating factor was there was no ‘explosion’ reaction, not really. Explosions were just the byproduct of some mass in a small volume suddenly trying to occupy a much bigger volume. If left unconstrained, that would just result in a movie-style fireball. Cool, but without much force. However, if in a container where that pressure could build, and then release all at once...

His steam bomb from his time with the dwarves was a perfect example. It was just flash-boiled water trying to expand into steam and not being able to. He knew from experience that the sudden cloud of superheated steam could definitely be dangerous, but at the same time it wasn’t that bad. Certainly not enough to seriously harm the sorts of creatures he was regularly facing. It was only when he’d encased it in mortar, and gave the steam a casing to build up pressure in, and shrapnel that it could propel outwards that it became formidable.

Of course, some explosives didn’t need some kind of container to undergo a genuine explosion. C4 came to mind, among other high explosives. In those cases, the air itself functioned as a sort of container, with the explosive trying to spread out faster than the speed of sound- that was, the speed of air- and creating a shockwave.

Of course, most detonations weren’t the result of high explosives, and so he’d probably need a container of some form. Fireballs were all good in Hollywood, after all, when they didn’t need actual danger and really preferred spectacle. But as a defensive tool? Well, there were three main possible ways to be injured by an explosion. Well, not counting incidental injuries like smoke inhalation or collapsing structures, anyway.

The first was the shockwave itself. If it was powerful enough, it could do some serious internal damage as it passed through squishy tissues and organs, bursting air vessels in the lungs and so on. Edwin was somewhat skeptical of its use against someone with Health, but at the same time it would probably be a great way to stress the Attribute, leaving them more vulnerable to other attacks.

The second was in some ways even more limited, and that was the direct heat of the explosion. Depending on what the explosive was, it could be seriously devastating, but for his purposes he doubted setting things on fire would be all that helpful. Overall, he figured it was a minor contributor in comparison to the other two, but bore mentioning.

The final and most functional method was kinetic projectiles. The idea was simple: put something strong but either brittle or small in the way of the explosion, and let the rapidly-onrushing gases blow it away. As the saying went, it’s not that the wind is blowing, it’s what the wind is blowing. Yes, it was technically about hurricanes, but it applied just fine to shrapnel as well. That was how grenades and guns alike worked, after all. Using an explosion to put a lot of kinetic energy into a metal projectile very quickly. And assuming he could get Bomb Throwing up to an appreciable level, the System would only make things stronger.

So, his task list… make a gun. He could do that. Grenades could come later, but he was hopeful to get a baseline idea of the strength of his explosives before he started bringing Skills into the mix. Grenades would definitely be affected by the Skill, whereas guns… probably not.

While perhaps the obvious candidate for making a gun was, well, black powder, Edwin… didn’t know where he could get the stuff for it. Neither Lefi nor Rillah knew where he could get saltpeter, and while thanks to Memory he knew he could synthesize it from guano, neither of his companions knew where he could find bat caves, either. Without that, the only accessible way to make saltpeter would take him at least a year, which he just didn’t have time for now.

He’d prodded his companions a bit as to the absence of the substance, considering he was pretty sure it had been in wide use for centuries if not millennia back on Earth. Apparently, it had just… never been needed.

According to the few mentions he’d found about it in the tower’s library, they knew of its existence, at least societally, but other than as a mild curiosity nobody really needed it. Thinking about its uses, he could almost understand. There were Skills for both meat preservation and fertilization, and alchemists cared more about magical substances over their more mundane chemical counterparts. Why bother performing the disgusting procedures that had been needed back on Earth to make it?

In all honesty though, it might well be just as easy for him to make nitroglycerin than it would be for normal black powder, and certainly more worthwhile. If he got his hands on sulfur he could probably make sulfuric acid, and once he had that, if he did get his hands on saltpeter somehow, he could make nitric acid. Mix those together with some glycerin, and well… boom.

All of that was still a ways off, though. He wasn’t stable enough- nor desperate enough- to start the year-long process of making saltpeter that was mixing manure with sawdust and letting it decompose for a year while keeping it wet with urine the entire time. Besides, he was an alchemist, he could come up with something better than that.

He hoped he could come up with something better than that. He had serious questions for whoever discovered that particular method of saltpeter synthesis. Like, come on.

Fortunately, while he might have been lacking in archaic yet common-on-Earth chemicals, he had elemental magnesium and phosphorus in abundance. It was… really kind of absurd. But was he complaining?

Okay, maybe he was, a bit.

-----

“Step.… up!”

True to his word, Lefi had actually gotten significantly better at teaching recently. It was really startling, but he supposed that was just what happened with Skills when he was Exceptional. A massive experience boost definitely would explain why he’d managed to improve, but there had to be more to it. Some Skill that boosted the efficacy of other Skills? He didn’t have any evidence for the idea, as there weren't any obvious candidates in the chaotic maelstrom that was Lefi’s skills, but it would explain why Lefi was seemingly good at everything, and could become a veritable master overnight.

While drills might have been boring, Edwin was immensely glad that his latest training sessions left just his Stamina exhausted, and not his Health as well. Plus, he was actually learning. Lefi had a lot of experience using his Skills, and when not just trying to get Edwin to figure it all out on his own, things went way faster.

“Step….. up!”

Longstrider flashed, and Edwin jumped forward almost 7 meters. Using the Skill properly in combat was significantly harder than Edwin had first thought it would be, because you still traveled through the intervening space. To the outside observer, it looked like he was gliding across the ground, and to someone in the know, it was really easy to intercept the movement unless you took really short steps. Doing that was fine, but if that was to be your primary use of the Skill there were better choices out there.

It was, apparently, why the Skill was a relatively low priority for combatants, who generally preferred Footwork (in the case of guards and mercenaries) or Marching (for soldiers). Lefi apparently disagreed, though. He said that the people who could only travel in a straight line were wasting their potential, and Longstrider was one of the single most important Skills when fighting.

Even Edwin knew that positioning was everything in a melee fight. But apparently the weaknesses of Longstrider were just too great most of the time. You couldn’t change directions mid-Stride any more than you could turn after committing to a normal step. Unless, of course, you had a shortcut.

“Step… up!”

Lefi, of course, had a Skill that just let him change direction mid-stride, ducking around obstacles at an absolutely insane pace, that was wholly separate from his Walking chain. Heel-Face Turn or something like that.

Edwin couldn’t do that. Not really.

But he could use Flight.

Longstrider and Flight just weren’t compatible. Longstrider only worked while his feet were firmly planted on the ground, and while he could have flight active, he couldn’t use it. Or at least, that was what he had thought for a while.

Lefi had pointed out that at the very least Edwin could use Flight to cancel Longstrider mid-step, which had its own set of uses. The experience was disorienting, because momentum with Longstrider was… wonky. From his perspective, he was going the same speed either flying or using Longstrider, but switching between them always included a lurch.

“Step….. up!”

Right now, he was practicing switching between them at a moment’s notice, and little by little, he was improving.

It was just a matter of practice, and with a good teacher… Well, anything was possible.

Edwin carefully broke off a piece of phosphorus from his supply. He had plenty for the foreseeable future, which was nice, but he made sure to keep it all underwater just to be on the safe side.

“It’s really nerve-wracking working with this stuff, so you know.”

“Does it really present any danger?”

“Honestly? I’m not sure, and I don’t want to find out. White phosphorus’ flames are hot enough to boil iron, so if pretty much any gets on my gloves they’re being thrown in the corner.”

Edwin wasn’t stupid, he was using Fey’s Caress under the gloves keyed off of a steel bracelet he’d picked up some time back, which should protect him enough. But he wanted to make sure Lefi knew that it wasn’t to be trifled with.

“Anyone without the right Skills got this on them? They’re in for a very bad time at best. If they somehow got any inside of them, well… I’m not sure if even you’d survive. Basically, this stuff is very bad news and you need to be careful around it at all times.”

“Understandable,” Lefi didn’t seem overly concerned about the substance, but Edwin didn’t really expect him to. The important thing was just that he knew how to behave in the lab. Obeying proper lab safety was, after all, one of Edwin’s main conditions for the adventurer to get some alchemy lessons. It was only fair, after all, given how much help he had been providing with Edwin’s Skills.

“But this will be something of a good, if volatile explosive. It ignites on contact with warm air, which I know I said before but it’s worth repeating, but that also means all we need to do to get it to explode is to just expose it to air. Now, it’s not instantaneous, but that’s not too much of a problem for me at least.”

“Your Firestarting,” Lefi asked, and Edwin nodded. The adventurer shook his head and chuckled, “I still don’t understand how you managed to transform a passive Skill into an active one.”

“Neither do I,” Edwin admitted, “Though Firestarting is already half-active at least, given it reaches out of the body.”

“Is that what you’ve found is the difference?”

“Well, it’s not a perfect definition, but it generally looks to be true. Anyway, that’s getting off-track again and don’t you have a Skill for that?

“So, by grinding this stuff into a powder, it will make it burn hotter and faster, but only if it’s not too small,” he explained, using a mortar and rough pestle to grind the waxy substance into granules, entirely submerged in a basin of distilled water.

“Why is that?”

“Okay, so fire needs air to burn, you know that right?”

“Yes, you said that this creates fire when exposed to air, I recall.”

“Well, I mean more generally… anyway, that’s not relevant right now. Basically, all fire needs air to burn… though that’s not entirely true strictly speaking, it just needs some kind of oxidizer,” he shook his head, “I’m getting distracted again. Basically, there needs to be all the stuff for your explosive to freely detonate available, and in this case that’s exposure to air. So, you want to maximize the surface area of the phosphorus relative to its volume, which if it’s all one block obviously isn’t happening and if it’s too small then air can’t get through but….”