Building NPCs in 5e & the Einstein Problem

There is a post on The Alexandrian blog, from 2007, called Calibrating Your Expectations, that I think about a lot, especially as I am building PCs and NPCs for my games. It’s long, but the short version of the relevant part is this: “Einstein was … a 4th or 5th level expert.” The line of thinking goes like this: as a 5th level expert, Einstein can have a +15 bonus to his Knowledge (physics) checks. With this score, he can answer the hardest questions in the field of Physics, those with a DC 25, by taking 10 on his check. The most vexing questions in the field might have a DC of 30, and Einstein would be able to answer those about 70% of the time, or 100% if he took a few minutes to think about it (and took 20 on the check).

The numbers change a bit for Pathfinder (which only allows one skill point per level to be placed in a skill, but gives a bonus for class skills), but the principle is the same. If I build Einstein as a Pathfinder Expert, it takes him until level 8 to get the +15. What this means for the PCs is obvious: a 15th level PC who has maxed out Knowledge (Engineering) and is reasonably intelligent might have 15 ranks, a class skill bonus of 3, and an intelligence bonus of 4. At a glance, that PC can build anything or determine the structural weakness of anything. They are both the best architect in history and the best demolitionist.

In 3rd Edition and Pathfinder, if a GM wants to create NPCs, we generally have to build them like a PC: with class levels, skill points, saves, hit points, and so on. The math has to make sense, so Einstein has to be an Expert who has maximized Knowledge (Physics), and has to have 7d8 hit points, and a +5 to hit. That’s pretty weird. I’m confident that Einstein couldn’t throw a punch that would land hard enough to damage the average person 75% of the time (maybe a little less if his Strength is below 10). Still, that’s the system.

5th Edition is completely different. NPCs can be built from scratch, and abilities  added on as needed. If my PCs come to town looking for a doctor, I don’t need much. In fact, if I want to build the best surgeon in the world, someone who can succeed at a DC 30 (“nearly impossible”) skill check related to medicine, let’s call him Derek Shepherd, I might build him like this:

Derek Shepherd

Derek Shepherd
Medium humanoid (human), lawful good
Armor Class 12
Hit Points 9 (2d8)
Speed 30 ft.
STR 10 (+0) DEX 12 (+1) CON 10 (+0) 
INT 18 (+4) WIS 18 (+4) CHA 16 (+3)
Skill proficiency: Medicine: +8
Tools: Healer's Kit +4
Senses passive Perception 9
Language: Common
Challenge 1/8 (25 xp)
Skill mastery: Medicine. Derek Shepherd has engaged in advanced 
study of medicine, and doubles both his proficiency bonus on 
Wisdom (Medicine) checks and his tool proficiency with healer's 
kits and other medical tools.
Specialization: Neurosurgery: Derek Shepherd has advantage on 
Wisdom (Medicine) rolls related to the brain.
Scalpel. Melee weapon attack: +4 to hit, one target. Hit: 2 (1d4) 
slashing damage.

Hacking Derek Shepherd

Derek Shepherd will almost always pass a medium difficulty Wisdom (Medicine) check, as long as he has his tools. He’s got a 90% change of getting a 15 or above in a hospital. If he’s looking at the brain, his chances go up to almost 100%. In that same hospital, he has a 15% chance of making a “nearly impossible” Wisdom (Medicine) check. That’s about right: if you watch a specialized doctor on television, they’ll often miss hard checks outside of their specialty. If Shepherd here is looking at the brain, however, his odds of diagnosing and fixing that impossible case go up to 28%, and two-thirds of the time he’s going to solve the very hard cases, without help, research, or trying again later. I think that about fits with what we’d see on TV: sometimes, they get it in one, and sometimes they need to come back later on.

Despite this, he’s a CR 1/8 creature. Most level 1 PCs could take him in one shot. He doesn’t wear armor. He has few hit points. He could defend himself with his scalpel, but it’s a precision weapon, not a combat weapon.

In 5th Edition, I don’t even have to make my “world-class surgeon” a level 7 character. I can focus all of his abilities on medicine and keep his CR low. This has a number of effects (whether you think they are features or bugs). First, it marks the PCs as special early on in their careers. Second: it means that the PCs get no benefit from rolling random NPCs for experience.

Third: it means that a creature’s “difficulty” in 5th Edition difficulty is entirely determined by its ability to fight. Townspeople don’t need class levels, ever. Your non-combat NPCs don’t need to be adepts, commoners, experts, nobles, or warriors. Even the town watch don’t need to be fighters, rangers, or warriors. They can just be NPCs.

I’m sure that other people have written about this, but I find it fascinating and want to play with it a little more. The best part is that this NPC took me just a few minutes to create. Sure, I could have done it in three lines (and I often do!), but this way I have numbers if I need them, if the group is attacked by a disgruntled former patient while he’s patching them up, say, but I haven’t sunk an hour into building a character the party might never see again.

What if I did want to build a combat NPC, though? What if I wanted someone who could accompany my group into the dungeon and help them out, as a cohort or as a plot hook? Can I build a character like that and keep it below a CR of 1?


Kalinda Sharma
Medium humanoid (human), chaotic 
Armor Class 13
Hit Points 22 (5d8)
Speed 30 ft.
STR 14 (+2) DEX 14 (+2) CON 10 (+0)
INT 14 (+2) WIS 12 (+1) CHA 16 (+3)
Skill proficiency: Deception +6, 
Intimidation +6, Investigation +5, 
Perception +5, Persuasion +6, Stealth +5
Tool proficiency: Thieves’ tools +2
Senses passive Perception 11
Languages: Common
Challenge 1/4 (50 xp)
Specialization: Investigation: Kalinda Sharma has advantage on 
Intelligence (Investigation) and Charisma (Persuasion) 
rolls related to finding information about people.
Sneak attack: Kalinda Sharma deals an extra 7 (2d6) damage when she hits a 
target with a weapon attack and has advantage on the attack roll, or when the 
target is within 5 feet of an ally of Kalinda that isn’t incapacitated and 
Kalinda doesn’t have disadvantage on the attack roll.
Pistol: Ranged weapon attack: +4 to hit, range 50/150, one target, reload 
(15 shots). Hit: 9 (2d6+2) piercing damage.

Baseball bat: Melee weapon attack. +4 to hit, one target. Hit: 5 (1d6 + 2) 
bludgeoning damage.

Hacking Kalinda Sharma, and NPCs in general

Kalinda took about the same amount of time as Derek, does quite a bit more damage, and is still just a CR 1/4. I wanted to keep all of her statistics in line with a PCs (unlike Derek, above), and she’s got enough hit points to survive alongside an adventuring party through the single-digit levels. If she does damage it will be noticed while still not outshining any single PC. Where she really shines, though, is in the skills. I could have given her more bonuses to Intelligence (Investigation) without raising her CR at all, because, according to the DMG, “skill bonuses have no bearing on a monster’s challenge rating” (279). She’s built to feel like a rogue but didn’t require me to build a rogue.

I could have built Kalinda at a higher CR, but that wouldn’t require me to change her skills or skill-related abilities. All it would mean is getting her some body armor, a few more hit dice, and an extra attack with the pistol. Creatures’ challenge rating, it seems, is only linked to their combat prowess. Everything else is icing (meaning that a DM can pile those extra features on at will, if it makes encounters more interesting).

On the DMG page 281 there are quick rules for adding class levels to a monster. In Kalinda’s case (though I think it’s rude to call her a monster), I may have added a couple of levels of rogue, but I don’t think that was necessary. She’s usable as is, and I don’t have to play a rogue to get use out of her.

Next time: Figuring out where Dungeon Hacking goes from here!

3 responses to “Building NPCs in 5e & the Einstein Problem

  1. Something related to this are spellcasters. They still use the 3e method of class levels (effectively) which makes for a burdensome NPC to make and run. I ended up making NPCs more like 4e with particular powers instead of spell levels. They can be created much quicker, run more easily and they tend to be more creative.


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