Wednesday, July 7, 2021

Number Appearing vs. Challenge Rating

So, I write this article after having a realization of the obvious. What I’m about to describe might be self-evident to you, but it felt like a big deal to me.

How did I come to this realization? I looked through the D&D 5th Edition Monster Manual, which I haven’t done in a long time. I recently started a campaign using Five Torches Deep (which I will eventually review), which necessitated my perusal of the bestiary.

 

Here's the situation: I was designing a mini-adventure for the party. The village elf tasked them with getting some honey from nearby giant bees so the elf could make salves of de-petrification for two party members turned to stone by a gorgon (the metal gas-breathing kind, not the snake-hair kind). I needed to develop some random encounters for the players to possibly run into on their way to or from the beehive, if the numbers came up right.

 

I decided that a good random encounter would be an ambush by orcs. Very original, right? But I was sick and pressed for time. Plus, it sometimes just feels good to have a classic encounter like that.

 

So I looked up orcs in the Monster Manual to get their stats, and this is what I found (sort of). This image is from Roll20, though what I found was obviously in the Monster Manual.



Which gives me almost all the info I would need for a random encounter with orcs. But there was one crucial piece of information missing: how many orcs attack the party?

 

I stared at the page, wondering where that information was. “Perhaps it’s in the 5e Dungeon Master’s Guide I lent my sister,” I thought. So as a stop-gap, I looked up orcs in Old School Essentials instead.



Sure enough, there was the NA (number appearing) stat, right where I expected it to be: 2d4 (in the wilderness. 1d6x10 in the lair).


So I ran the adventure and, as it turned out, the party encountered five orcs on their way to the beehive (since they were travelling in the forest and rolled a 2 out of 6 for wilderness encounters). One of them was knocked unconscious, but they managed to kill four of them (including the leader) before the last ran away.

 

Overall the party was very badly wounded and lost a lot of HP before they even made it to the beehive, making it a pyrrhic victory. Of course, the beehive itself was much more interesting and deadly as a result ;)

 

Had they rolled a 1 or 2 on a d6 on the return trip, they would have encountered an inquisitive treant. But alas, they rolled a 5.

 

That question about the number appearing still stuck with me afterwards, though. Why couldn’t I find the number appearing in the 5th edition Monster Manual? I used to run 5e, back in the day. How did I do it then?

 

Eventually, it "clicked" for me: 5e doesn’t have the “Number Appearing” in its monster descriptions. It uses CR (challenge rating), instead.

 

Again, this may seem obvious to you. But it felt like a real lightbulb moment for me, partly because this feels like a fundamentally different approach between “new-school” and “old-school” systems. One that has profound implications for the kind of game you play.

 

As usual, I am not the first one to come to this realization. A similar realization was made on RPG Stack Exchange over four years ago. I have included a quote of SevenSidedDie’s post below:

In AD&D and earlier, combat encounters are intended to be somewhat more naturalistic and organic to the setting. The idea of “number appearing” follows this philosophy, indicating how many creatures tend to be encountered when that type of creature is encountered. This is regardless of how difficult it would be to fight that many of that type of creature. DMs can also easily choose more or fewer creatures for a situation, as appropriate to the situation — again, because the game is concerned with giving the DM tools for deciding what makes naturalistic or adventure-plot sense. The players are expected to scout ahead and learn about the dangers around them, to make informed decisions about whether and how to engage them. (A party that fails to do this is making a strategic error.) A war party of 300 orcs was possible for a 1st-level party to run into in AD&D.

D&D 3rd edition and later use a different encounter design philosophy that is orthogonal in purpose and execution. Instead of asking “if they meet an orc, how many are they likely to meet?”, the game instead asks “how many creatures of what toughness make for a good combat challenge, and how many such challenges should there be in a day?” This philosophy means that “number appearing” isn't directly useful rules-wise, and instead a measure of the creature's combat difficult is needed. This is what Challenge Rating is.

So in old-school games (such as B/X and AD&D), the number of monsters encountered was more “naturalistic,” considering the type of creature and their social organization. Conversely, in “new-school” games, the rules expect the Dungeon Master to have the party encounter an “appropriate” number of creatures using the Challenge Rating (or their XP value).

It reminded me a bit of the difference between Morrowind and Oblivion. While both of these games have some degree of level scaling, the level scaling is much more pronounced in Oblivion. In other words, the monster and treasure encountered in the game world leveled with you. You could enter a dungeon as a level 1 character in Oblivion to find rats and iron weapons, but enter that same dungeon at level 10 to find spriggans and dwarven weapons.


The same isn’t quite as true in Morrowind. I remember wandering around as a low-level character, entering a random tomb, and encountering a Bonelord. I promptly shut off the Xbox out of fear.


 

It is important that we don’t "paint with too broad a brush," however. Even in early D&D, there is some indication in the text that “balance” should be considered when designing encounters for adventurers.

 

The first indication is that monsters are scaled to the level of the dungeon they’re encountered on. In a typical dungeon, 1HD creatures are encountered on Level 1, then 2HD creatures are encountered on level 2, and so on. As the party ascends in character levels and descends deeper in the dungeon levels, their capabilities and the challenges they face are commensurate.

 

You can see some examples of this idea of “balance” in harlandski’s quotes from Moldvay’s rules in these posts, where the Basic set says, “The Wandering Monster tables (below) give a balanced mixture of monsters for the dungeon levels,” as well as, “Most Wandering Monsters are the same level as the level of the dungeon (...) The "Number Appearing" of some monsters has been adjusted to make them more appropriate for encounters on a dungeon level" (emphasis added).

 

Over at Delta’s D&D HotSpot, Delta also pulled out some references to this idea of scaling as far back as OD&D. For example, a footnote to the Monster Reference Table gives the referee the “option” to “increase or decrease according to party concerned.”

 

There is also some indication in OD&D that the number of monsters encountered was adjusted according to the number of party members, rather than their level. According to Delta, the Monster Determination table gives the following instruction:

 

If the level beneath the surface roughly corresponds with the level of the monster then the number of monsters will be based on a single creature, modified by type (that is Orcs and the like will be in groups) and the number of adventurers in the party. A party of from 1-3 would draw the basic number of monsters, 4-6 would bring about twice as many, and so on. The referee is advised to exercise his discretion in regard to exact determinations, for the number of variables is too great to make a hard and fast rule... 

 

So it would be unfair to say that the idea of scaling encounters to the party’s level, or to the number of characters in the party, is completely a “new-school” mindset. That idea has clearly been around in some form since the inception of D&D.

 

However, it is fair to say that the idea of scaling encounters to the party’s abilities is much more prevalent in new-school games (from 3rd edition forward). In fact, it is so prevalent that the 5e Monster Manual omits a “number appearing” entry in its monster descriptions, instead providing Challenge Rating.

 

Sort of like Morrowind and Oblivion. Level scaling is present in both, but it is much more noticeable in Oblivion – such as when every bandit you encounter suddenly has glass armor and daedric weapons.


How did every bandit ringleader come to possess glass armor and Daedric weapons? The world may never know.

It is important to recognize that these assumptions have an impact on the game, however. If the players can “rest easy” knowing that most encounters are scaled to their level, they are much more likely to enter combat frequently and confidently. The world (including dungeons) also becomes much less scary and dangerous, as a result.

 

However, if the players know that the difficulty of encounters is “up to the dice,” I think it encourages them to play with much more caution and creativity. This lack of level scaling encourages investigative and careful play, in my experience.

 

Though really, given the presence of some degree of level scaling in early D&D, it seems to me that most folks would likely use both of these measures.  When it comes to Number Appearing and Challenge Rating, why not list both?