“I,” Harriet declared some time later, “really hate this world.”

“I don’t think it’s so bad,” her mother disagreed unconvincingly. “There’s upsides. The fugue-traveling at least skips some interstitial boring bits.”

“I’m with our daughter on this one, honey.” Cassandra’s face betrayed her momentary surprise. “Just because the tunnels are alike,” Jason clarified unhappily, “doesn’t mean I don’t treasure every moment I get to spend with my loved ones. Isn’t that the point of these family trips?”

“We call it fast travel,” Trio offered. “Turns out to be faster for most people, ‘cause you don’t have to remind yourself to keep up the pace, and it’s near enough to instant in your memory.”

“Like when I walk to school,” Harriet mused, “and I don’t have any memory of the distance between leaving the house and getting to class.”

“That’s because you read the whole way there, which you should really stop doing.”

“First off, mom, shut up—and second, yeah probably on both points.”

“With proper humility and grace,” gloated the mother in question, “I’ll take that win. Trio, we heard someone mention the Rule of Tuck earlier. What’s up with that? And what else can we expect around here?”

The miner blanched. “All Gods, we hadn’t considered you might not know. Well, ma’am, let’s just say it’s one thing to disarm a few traps they left on a lark, but we do not engage kobolds. That’s the Rule of Tuck; unless you’ve got strategic-class assets, and we’re talking seventh level spells, and not singular. Spells like Fire Storm—”

Fire Storm

7th-level evocation

Casting Time: 1 action

Range: 150 feet

Components: V, S

Duration: Instantaneous

A storm made up of sheets of roaring flame appears in a location you choose within range. The area of the storm consists of up to ten 10-foot cubes, which you can arrange as you wish. Each cube must have at least one face adjacent to the face of another cube. Each creature in the area must make a Dexterity saving throw. It takes 7d10 fire damage on a failed save, or half as much damage on a successful one. The fire damages objects in the area and ignites flammable objects that aren't being worn or carried. If you choose, plant life in the area is unaffected by this spell.

“—and Regenerate, but if we had more’n a few of those in the Realm, folks like me wouldn’t be shit out of goddamn luck with our fingers, yeah?”

Regenerate

7th-level transmutation

Casting Time: 1 minute

Range: Touch

Components: V, S, M (a prayer wheel and holy water)

Duration: 1 hour

You touch a creature and stimulate its natural healing ability. The target regains 4d8 + 15 hit points. For the duration of the spell, the target regains 1 hit point at the start of each of its turns (10 hit points each minute). The target's severed body members (fingers, legs, tails, and so on), if any, are restored after 2 minutes. If you have the severed part and hold it to the stump, the spell instantaneously causes the limb to knit to the stump.

“Kobolds, huh? Why? I could put an arrow through one fifteen times outta twenty. And none of them is gonna survive one.”

Trio stopped in his tracks, spinning around to face Harriet. “And the other seven?” His hands came down on her shoulders as he looked down—and further down—at her, her complete non-reaction outside of an intense stillness betraying her readiness for his movement to have been violence. “What about the other fucking seven, girl? Their basic squad is eight of ‘em, and if you and your parents kill one each, you know what happens? One fucker walks into knife range of any of you, and you blink an eye and one of you’s dead.”

Ensure your favorite authors get the support they deserve. Read this novel on Royal Road.

“My dad’s tougher than—”

“Yer dad’s a Paladin with an enviable Constitution and good armor, maybe twelve health and seventeen armor class?”

“That’s about right,” Jason interjected with a respectful nod.

“There’s five kobolds. One of ‘em gets into dagger range, the other four get a sling attack with advantage, yeah? Four damage with a +4 to hit. You know enough math to—”

“Any given attack needs a fourteen to hit against my dad’s AC,” Harriet said dourly. “That’s a seven-in-ten chance of missing, and if it’s got advantage, it needs to miss twice—seven times seven is forty-nine, and that’s close enough to half that we’ll call it a coin toss. They need four hits to kill him, or alternatively that’s two misses to survive.”

“You—”

“We’ll take the worst case scenario and say that two of them are in a five-foot range.” The normally-mischevious girl with the suddenly cryogenic-cold eyes trampled over his interjection. “They all have advantage. This also makes the math easier, because the odds are uniform, and we can just say it’s the inverse odds of zero misses plus one miss. The chance of zero misses is fifty-fifty to the fifth, which is…” Harriet frowned. “Twelve-five, six-two-five, three-one-two-five, three and a bit percent. The chance of one miss is… there are five different permutations of single-hit, and each has the same individual probability as five hits. So times five—no, we’re adding the two, times six, but actually, five and then one is easier, three-one-two-five becomes one-five-six-two-five. The two two-fives become a five, one-nine-eight, almost exactly a one in five chance.”

“A one in five chance of surviving! That’s why the Rule of—”

“You got that barely wrong, honey.” Cassandra smiled at her daughter. “Deriving it from first principles is nice, but the binomial distribution is right there. Don’t reinvent the wheel. You got stuck in the swamp running the permutations.”

The halfling girl’s shoulders slumped. “Sorry, mom.”

“Don’t you sorry me, little mischief, you don’t even like math and you haven’t studied statistics yet, not properly.”

“Yeah, yeah, I know you thought I should do it before Calculus.”

Harriet waved her mom off, not straightening from her slouch. She took a slow breath, letting it out, then another. Jason shook his head meaningfully at Trio as the man opened his mouth to interrupt, and after one more breath Harriet opened her eyes again.

“Obviously five successes on five is still the same. The binomial distribution is n-choose-k times p-to-the-successes times q-to-the-failures, but since it’s a fifty-fifty, that’s just five-choose-4 times one half to the number of trials, which I already know, that’s the same three-point-one-two-five percent. The formula for n-choose-k is n-factorial divided by open paren k-factorial times open-paren-n-minus-k-close-paren factorial, close paren. Five factorial over four factorial times one factorial, a-k-a five factorial over four factorial, which is five.

“So five times—motherfucker!” She suddenly buried her face in her hands, groaning. “Mother goddamn fucker!”

“Language, kiddo,” Jason murmured with mirth in his eyes.

Harriet didn’t seem to notice him or what he’d said. “I had the stats right and I fucked up my addition! I literally fucked up adding two numbers, fuck everything sideways with a cactus!” She took another deep breath. “The five kobolds have an eighteen and three quarters percent chance of killing Dad in one round, but that assumes all three of us kill a kobold and go before them all, and they’d probably kill Mom first anyway, and can we stop talking about this and just agree not to make them mad?”

“Kid,” Trio said with visible relief leavened with brand new worries, “nothing would make me happier. But… keep it on the downlow that you’re all touched by the Unchained, yeah?”

All three of them squinted at him in physical unison. “Unchained?” Cassandra kept her voice steady as she pushed at her normally-reliable cheat skill in its silence. Reference Query, she subvocalized with intent, definition of UNCHAINED given context.

ERROR

ERROR

PROCESSING

ERROR MESSAGE FOLLOWS

EEEER RRRRR OOORR EERO RRR ORE ROOO OO REE ROO R ER ROR

“You don’t know—well, obviously not.” Trio shrugged. “Unchained’s a God, but you won’t find any mention in the books, and no other God’s gonna say shit. When you do something outta skill instead of having to go through the System? That’s Unchained. And nobody likes you folks, ‘cause you’re unpredictable and heretical or whatever.”

“That’s nice,” said Cassandra distractedly, with about one percent of her attention. “So, no making the kobolds mad. What’s our other opposition likely to be? We already know about the goblins, hobs, and human acolytes.”

“And traps,” Harriet said sheepishly. “A buncha different kinds of traps. And we’re in a mine, so I wouldn’t be surprised to see bats, snakes, that sorta thing. Speaking of traps, tripwire, like the last one but way worse?”

“Goblin work,” Trio said with a nod. “After your daddy spotted the kobold ones and showed ‘em to you, I’m not surprised you can find these. Let’s get past this set of whatever, make sure we’re clear, and we can talk about what else we might find.”