D&D 5E DM's: How Do You Justify NPC's Having Magic/Abilities That Don't Exist in the PHB?

[Lanefan]

And that's when that particular DM who has the issue decides to make the NPC mechanics into mechanics the new PC can use and take. Nothing wrong with that, and is probably a good design challenge for the DM to take on. To me... that's quite surmountable.

But it's not something the designers of 5E themselves have to officially do for players, because it was not one of their design decisions when they made 5E.

Indeed, though I still think they made the wrong decision here.

My own personal take on the question is that random new abilities just "show up" in the game world all the time, every time a new player's guide like Xanathar's or Tasha's gets published or a new monster manual is released. Which means there are always these "background" abilities out there being used, that just aren't being highlighted by the PCs or the creatures they are fighting.

Perhaps, but I really try to avoid this if I can - once the campaign starts, the rules in place at that point are (as far as possible) locked in for the duration. Any later changes that affect anything currently or previously seen in the campaign need some sort of explanation in the fiction, which can sometimes be tough if not impossible to pull off and other times trivially easy.

There's always monsters out there nobody's heard of; and there's also many monsters in the MM that in almost 40 years have yet to see the light of day in my games. There's always new spells being researched and developed, and maybe one could use that same rationale to explain the appearance of new abilities for non-casters. But none of this explains why a PC [pick a class] works one way and an otherwise-equal (i.e. same species, same general degree of competence, etc.) NPC works differently.

Put another way, isn't it better to assume that any NPC in the game world could someday become a PC?

So there's no problem whatsoever for PCs to not have the functionality to take these features-- either because they are specific monster abilities from the MM... or because they are PC abilities they just aren't aware of yet because they will only finally show up when a new player's guide gets published.

Consider my example above, though, with the recruited NPC Fighter. Nothing new has been published, yet in the fiction before she joins the party she has NPC abilities a PC can't have and doesn't have some PC abilities. Then she becomes a PC. What happens next, and how do you plausibly explain it in the fiction?

Does she stay exactly as she was, thus forever working differently in her mechanics than any other PC Fighter? (and if yes, then in the interests of fairness I then have to allow every Fighter access to those same mechanics, as I've just set a precedent) Or does she snap-change to mirror the mechanics and abilities of PCs, without any training or in-game reason or rationale behind it? Remember, in the fiction the PCs already know what she can and can't do; that's probably why they recruited her!

 

[James Gasik]

Well sure, for example, the NPC Gladiator in the Monster Manual, who has a special ability to deal an extra die of damage with their weapon attacks. How do they do that? How does every Gladiator do that? Why can't a Fighter get this ability? I mean, heck, being enlarged to ogre size just nets you an extra d4 damage; this guy can do 2d12 with a greataxe!

Sure, the Doylist answer is: "it's a math fix so the monster is an appropriate threat for their challenge rating". But the Watsonian answer is "?????.....reasons!". I know people in real life who will gnash their teeth any time something about the game "doesn't make sense", but don't even bat an eye at monster abilities...and this is an ability, it's even called out in the text and given a name, "Brute" (ironically, the Gladiator also has an ability that players can have, "Brave", the same as the Halfling ability. I guess there are no Halfling Gladiators outside of a long-running webcomic).

 

[Vaalingrade]

Why can't a Fighter get this ability?

Oh! I know! Because Fighters don't deserve abilities!

 

[Irlo]

The gladiator is a good example of different ways to look at abilities. Rolling an extra die of damage is not meaningful to a character in the world — not something to be learned. It’s just a different way to calculate damage. There are methods that PCs can learn that allow them to do more damage.

It seems to me fundamentally different than the ability to cast a certain spell.

 

[Micah Sweet]

Also bear in mind that some participants are looking for rules guidance, and if you chime in with how you would homebrew things without saying that’s what you mean, it might be confusing.

When have I hid the fact that I homebrew?

 

[Incenjucar]

I'm not against the simulationist approach, though it's a lot of extra work, but even then the PCs live different kinds of lives from most other creatures, so the options they share will not be 100% the same even then.

"Why can't my barbarian do the same things as the barbarian chieftain" can be as simple as "you aren't doing anything a barbarian chieftain does".

 

[James Gasik]

The gladiator is a good example of different ways to look at abilities. Rolling an extra die of damage is not meaningful to a character in the world — not something to be learned. It’s just a different way to calculate damage. There are methods that PCs can learn that allow them to do more damage.

It seems to me fundamentally different than the ability to cast a certain spell.

Are we only talking about spells? I thought any ability that NPC's had and players didn't was part of the discussion. Also, I'm pretty sure that a character in the world would find the Brute ability meaningful. "So when I swing my axe, it kills things twice as fast? Yes please!"

 

[Vaalingrade]

I'm not against the simulationist approach,.

I am. Vehemently.

 

[James Gasik]

I'm not against the simulationist approach, though it's a lot of extra work, but even then the PCs live different kinds of lives from most other creatures, so the options they share will not be 100% the same even then.

"Why can't my barbarian do the same things as the barbarian chieftain" can be as simple as "you aren't doing anything a barbarian chieftain does".

To be followed by "what does a barbarian chieftain do, and can I do that?"

 

[Bill Zebub]

If ANYTHING about that character's mechanics change due to this move from NPC to PC, there's an insurmoutable design-level problem with setting consistency; because the character herself hasn't changed a bit in the fiction.

I mean, I find it weird enough that you let a player take over an NPC as a PC. But, sure, let's do it.

First of all, I'm not sure what you even mean by "talking and figuring out the difference between PC rules and NPC rules". WTF is that? Like, the NPC gets triple damage on a crit, and by talking about their experiences they're going to figure that out? That's crazy. The rules are an abstraction of the fiction; it's not a 1:1 correlation.

Ok, then let's assume this NPC becomes a PC. (Again, weird, but whatever.). I don't find it "insurmountable" at all that the mechanic changes. Fluff it however you want. "Yeah, it's weird, but ever since I joined you guys I just don't hit as hard. Must be Tenser's cooking."