The Alphastream Game Design Blog
Two of my favorite people on Twitter, Mike Shea and Enrique Bertran, were talking about monsters. Mike makes the great point in a recent blog post that when choosing monsters for an adventure, you should first think about the story. The monsters should make sense.
Enrique pointed out that sometimes the monsters that fit the story won’t present a satisfying challenge. His 12th level characters are steamrolling his monsters. There is a reason for that.
If you have trouble challenging your players, you aren’t alone. From forums to Discord to Twitter, lots of DMs are crying out for help.
Some of this is to be expected. In any RPG, the DM has one brain. The players have 4-6 brains. The players know their characters superbly, while this may be the first time a DM is running a particular monster. This is not a bug. It’s a feature, because we want the players to win.
However, we want the players to feel challenged – at least when we are intending to design a harder fight. D&D 5E has four encounter difficulties: Easy, Medium, Hard, and Deadly. We can pick monsters and use either the DMG or Xanathar’s to create an encounter appropriate for the players. Except… the math doesn’t work.
I don’t think the encounter guidelines are that bad. In general, it’s an okay system for selecting different monsters and seeing how hard they are. The problem is with the monsters themselves and how little damage they inflict.
We can also argue that the monsters can’t counter what a typical party does, but I again believe that’s a feature. We want the characters to shine. But we want them to feel challenged as well.
Let’s take an average class like the Rogue. Starting Hit Points are 8 plus Con modifier. Assuming a Con of 12, that’s 9 Hit Points. Each level, they gain 6 Hit Points (5 + Con mod). A level 5 rogue has (9+6+6+6+6) 33 Hit Points. (Most classes have d8s for hit points. The barbarian has d12, the fighter/paladin/ranger have d10, and the wizard/sorcerer have d6.)
If we look at our encounter guidelines, a fight with three CR 3 creatures against five PCs would be halfway between Hard and Deadly (4,200 XP). On average, a CR 3 monster inflicts about 20 points of damage (the DMG guidance for building monsters says 21-26, but actual monsters WotC creates tend to deal less damage than the guidelines). For CR 3, the average Attack bonus is +5.
So, if our rogue has AC 15 (Studded leather, Dex 16), the monster will hit half the time and inflict an average of half its damage each round… or 10 damage per round. The monster needs 3 rounds to drop our rogue.
Now, that might happen, especially if 2 or all 3 of the CR 3 monsters gang up on our rogue. But our rogue can Disengage as a bonus action, and is accompanied by other companions. Let’s say the four other allies each have similar Hit Points. The total pool of Hit Points is 165 (5*33). The total damage all three monsters inflict is 30 a round, assuming they hit half the time. They need 5.5 rounds (into the sixth round) to defeat all four PCs. Most combats don’t last six rounds. And, realistically, PCs are smart. They will focus fire, quickly eliminating one of the foes. They also may have spells or abilities to turn the tide in their favor in various ways. And, importantly, they can heal each other and pop back into the action.
My point is, on damage alone, it’s unlikely to be true peril. That’s okay, because we don’t need true peril for the game to be fun (more on that next time). However, this will get worse over time for the DM. And, in all of my examples, consider that we aren’t taking into account the wild shaped druid, the barbarian’s Hit Points, the paladin’s absurd AC (with shield due to multiclassing, of course). Players are motivated to win, even if they aren’t super optimizers.
It may be worth mentioning that the encounter math is imperfect in several ways. First, monsters themselves vary greatly as to how challenging they are. A CR 1/4 flying sword is +3 to hit and deals 5 damage once. A CR 1/4 wolf gets pack tactics, has +4 to hit, and deals 7 damage and can knock you prone.
Second, the way encounter difficulty is challenged can mean the same group of monsters work even if you level every character up! Five 5th level PCs facing three CR 3 creatures and one CR 1 creature is between hard and deadly. If the characters are 6th level… the same group of monsters is still between Hard and Deadly! (Even if you use the rules in Xanathar’s, we see this happen at various points in the tables.) In other cases, adding even a very weak monster will throw an encounter into another challenge category, even if the monster adds no actual challenge in play. It’s an imperfect system, and one that is hard for DMs to gauge.
But the point here isn’t to blame the encounter system. I don’t love it, but I don’t believe it is as big a problem as the underlying monster math. Let’s look further.
When our party levels up, they are gaining 6 Hit Points each level. (Okay, the rogue is. The fighter gains 6 + Con, so probably 8-9 hit points each level. The barbarian is getting 7 + Con, so probably 9-10 Hit Points each level!)
How does monster damage keep up with this? It doesn’t. On average, the monsters WotC publishes gain 5 damage with each CR, but some levels they get none at all.
A party of five 8th level rogues has 51 Hit Points each, for a pool of 255 total Hit Points. An encounter with four CR 4 creatures is between Hard and Deadly. CR 4 creatures deal an average of 25 points of damage a round and have a +6 attack bonus. Even if the monsters hit on every single attack, they need to get into the third round to defeat the party. If they hit 75% of the time, they need to get into the fourth round of combat, and if they hit 50% of the time, into the sixth round of combat.
The above math isn’t in the DM’s favor, and it gets much worse the moment one of the four monsters is dead or unable to attack. Spells like hypnotic pattern, sleep, banishment, and counterspell prevent that damage… sometimes for several rounds. It all adds up to an even worse scenario. This is a fight that’s supposed to be between Hard and Deadly. Our damage output drops significantly if we have a medium challenge, calling for one fewer monster.
How about level 12? A party of five 12th level rogues has 75 Hit Points each, and a total pool of 375 Hit Points. An encounter with four CR 6 monsters is halfway between Hard and Deadly. A CR 6 monster deals an average of 35 damage a round and has a +6 attack bonus. We get roughly the same results in terms of the rounds of combat needed, but we all know our players are even smarter and their PCs even more capable.
It gets worse when the party faces a single creature. A CR 16 Steel Predator is between Hard and Deadly for this party, but it deals 46 damage a round if all three attacks hit. It will need 8 rounds to defeat all the characters, even if every attack hits! I didn’t account for the “Stunning Roar,” but even if half the party is stunned for two rounds, it’s unlikely to change the outcome.
Next week we will look at what DMs can do. Yes, the solution is often to add damage, but we will talk about the technique behind doing so, as well as important factors to consider when you do alter the challenge level.