Rule of Thumb: A lot of times, when I am making an encounter, I flip through an adventure like Curse of Strahd. I find an area that is the same level as my heroes and I look at the encounters. It's an easy way of checking out monsters that are suitable for your group. If you're running a low level game, Lost Mine of Phandelver from the Starter Set is invaluable in this regard.
The Basics of Encounter Building
grab this pdf from the wizards site. It lists every monster in the Monster Manual by challenge rating! It makes this much easier.
I'm not a math guy. These encounter rules are a little tricky for those us who are numerically challenged. I'm going to try and explain how it works. Encounters are broken into categories: Easy, Medium, Hard and Deadly.
How Many Encounters are there in an In-game Day? Check out "The Adventuring Day" (DMG page 84). It says that most adventuring parties can handle 6-8 medium or hard encounters per day. Most groups will need to take a total of two short rests between these encounters if they are able.
How Many Encounters Before You Gain a Level? Level one and level two go by really fast. From what I understand, levels one and two are sort of "training wheel" levels so new players can ease into learning all of the things you can do in D&D. Check out "Character Advancement" (PH page 15):
- Going from level 1 to level 2: 300 XP (That's 6 medium encounters).
- Going from level 2 to level 3: 900 XP (That's 6 medium encounters).
- Going from level 3 to level 4: 2,700 XP (That's 12 medium encounters).
|The challenge rating of a monster is listed in the stat block|
A few notes:
- Powerful Monsters: If the challenge rating of a monster is higher than the party's average level, it says to be very careful using them at low levels.
- Certain Abilities have Impact: Also be aware that certain monster have powers that make thing rough for low level characters.
- The Number of XP Might not be Exact: Making encounters is a little tricky if you're shooting for the exact XP number. Sometimes you'll be a little over or under the number of XP you want.
- 2 monsters = x1.5
- 3-6 monsters = x2
- 7-10 monsters = x2.5
- The party is surprised.
- The enemy has cover.
- The heroes can't see the enemy.
- An environmental effect is doing damage to the heroes.
Easy Encounter: 200 XP
Single Monster: Challenge 1 monsters are worth 200 XP each! That's nice and easy. Let's pick some:
- A ghoul
- A harpy
- A kuo-toa whip
It's really weird to try to backtrack mathematically. I know a lot of you D&D players are very smart so this probably isn't a problem for you. It takes me a minute to figure some of these out. Anyway, here's some pairs of monsters that are easy for your level 2 heroes to defeat:
- Bullywug and a reef shark
- Goblin and a hobgoblin
- Panther and an orc
- 3 crawling claws and 3 cultists
- 3 homunculus and 3 kobolds
- 3 vultures and 3 tribal warriors
Medium: These are average encounters for your level 2 heroes. The total value is 400 XP worth of monsters.
One Monster: The closest would be a challenge 2 monster, which are worth 450 XP. Usually I go under the XP total, but in this case I think we're OK. There's some really cool monsters that are hard to resist:
- Gelatinous Cube
- Black bear and a brown bear
- Hobgoblin and a bugbear
- Scout and a death dog
- 4 cultists and 2 acolytes
- 4 kobolds and 2 pteranodons
- 4 guards and 2 flying swords
One Monster: A challenge 3 monster is worth 700 XP. Let's go ahead and grab one, they'll be fine!
- Displacer beast
- Green hag
- Goblin boss and a dire wolf
- Copper dragon wyrmling and an imp
- 2 spies
- 6 zombies
- 3 skeletons and 3 violet fungii
- 2 smoke mephits, 2 steam mephits, 2 mud mephits
One Monster: Challenge 3 monsters are 700 XP, sounds good enough to me! Let's pick some:
- Hell Hound
- Water Weird
You Must Use Your DM Senses
Knowing Your Group: If you are running a campaign, building encounters is no big deal. You are going to know what your group can handle pretty quickly because you play with them every week. Between sessions, when you look at monsters, you're going to know your group's go-to powers. If the group is loaded up on fire damage, you will know that throwing creatures immune to fire is likely to be more challenging to them than an average party.
Test Fights: Sometimes I run "test" fights. My group was going to fight Tiamat at the end of Rise of Tiamat, so to prepare for it I slapped my custom Tiamat stats (slightly lowered) on another dragon for them to fight a few sessions before the Tiamat battle would take place. I took notes during this fight. Was the AC too high? Did the monster do too much damage? Did it feel like a threat?
That's a nice way to make sure that your climactic battles are challenging but not too overboard.
In general when making encounters, I also always aim low. I err on the side of too easy. When I run a session, if things are too easy, I add monsters to the subsequent encounters until everything feels right. Haphazardly throwing deadly monsters at the group can turn your campaign into a car wreck. Either your group is going to die or you're going to have to fudge things and everybody will sense it.
Fudging like that cheapens things. We all have to do it sometimes, but avoid it when you can. If the players feel like you're saving them, it takes their feeling of achievement away.
Re-Skinning: A lot of times, people will ask me how I statted out a monster in my 5e Planescape game. All I do is take a monster from the Monster Manual and change the name. I'll look up the creature I want to use from an old edition and add some of its powers.
As an example, a few weeks ago, I used a rust dragon. I grabbed green dragon stats from the 5e Monster Manual - the AC, the bonus to hit, the damage, some of the legendary actions, etc. I kept the DC and the damage from the breath weapon, but I changed it to the rust dragon breath from 2nd edition. It takes one minute!
He's talked about this before in his 4e DM Experience columns. Even in 4e, he just threw whatever he wanted at the heroes.
There is a certain art to this. When you run a big, chaotic encounter, you don't have to have every bad guy attack on every round. Some might stand there and cackle nefariously. Other villains might try to do something else: escape, steal something, tip something over, whatever.
The trick is to make sure it doesn't feel obvious that you're holding a bad guy back on purpose. You should establish that villain's motives well in advance so it doesn't feel tacked on.
Your Mentality is Key to Engaging Encounters: When you are running a game or working on material for your campaign, you should always keep the mindset of "what if this was real?" I don't mean that literally, I mean you should think about what things are really like in your world. Not every enemy should be just running up, doing damage and trying to kill the PCs.
When your group is in a city, the guards have to follow rules. Some of those guards don't want to kill anybody. Some of them might secretly agree with whatever shenanigans your heroes are up to. Things like this are key. Say the group is getting beat down by these guards. One guard secretly likes whatever cause the group is behind. The guard covertly helps the heroes flee the scene by creating some false alarm or distraction.
Think about what a monster would do or feel. The group is going through the forest and they stumble on an owlbear. The owlbear hoot/roars and the group attacks it.
The owlbear might just have been looking for a snack. Maybe it doesn't want a fight. Maybe it's ill.
Don't Fall Into a Rut: It's good to have variety when it comes to encounters. It is so easy to fall into the trap of having every encounter in your game be nothing but fights to the death. It's happened to me many times. It is a rut that you want to avoid, because I've found that it can make your campaign feel stagnant to everyone. It gets too one-dimensional. Sessions become a collection of battles and little else. It starts to feel like a chore.
NPC Motivation: You always want to reset your brain and think from the perspective of the NPCs in the campaign world. Think about their motivations. Some NPCs will try to trick heroes. Some will do anything to help them.
Some bad guys might want something the heroes have and remember, there's a million ways for them to try to get that thing that doesn't involve four orcs in a square room.
Not that I am trying to poo-poo the idea of combat. Combat is great! It's fun! Just keep in mind that variety is the spice of life. Players love using their skills and spells in new ways, in new situations. I think it's a great idea to go out of of your way to make encounters where a character's skill or spell will save the day.
It's hard to sit in front of a blank piece of paper or computer screen and come up with a cool encounter that will be different and exciting. Here's some encounters that I like. Maybe they will give you ideas of your own:
The Endless Stair: I ran this adventure when I was a kid and really made a mess of it. It's all about these mysterious translucent stairs that spiral up into the clouds. Where do they go? Spoiler alert: A dungeon.
Today, I love the idea of running an encounter on those stairs. There's no railing! You could have flying creatures attack. The danger here wouldn't be damage from the monsters - it would be making sure you don't fall off! All you need is some flying creatures that can push people off of the stairs and you have yourself a fun, crazy encounter.
Falling Into Hell: I know I got this idea from somewhere online, but I can't remember where. I ran a combat in 4th edition that occurred as the characters were plummeting into hell. The whole thing was in mid-air battling flying devils. It was a ton of fun. I can't remember how they survived the landing - I think they fell into a pool of molten iron! They took plenty of damage from the devils but once they'd slain them, they still had a few rounds to buff/protect themselves from the landing.
Theft: This is another one I ran when I was a kid. This was in an adventure from one of the Lankhmar setting books. Basically, the group had to infiltrate a costume party at a noble's house and steal a magic item (the "star of the east") that was on display. On that day, I learned a valuable lesson that has served me well since: players love in-game parties. Every single time I run one, it is a hit. Additionally, the whole idea of this kind of mission is so different that it is very refreshing and can really energize a campaign.
The Evil Sword: I love Bane of the Shadowborn, an old 2e Ravenloft adventure about an evil sword named Ebonbane. It could animate weapons, including the ones the heroes had! It was so different. All these hovering knives just slicing and flying around as the group's own weapons turned against them. You have to be careful with things like this because players definitely feel weird about it. It has a bit of a "the DM is screwing with me" vibe. Once in a great while, however, I think that it's OK to do it.
The Bounty Hunters: In a Ravenloft campaign from way back when, I had these three unique bounty hunters chasing the PCs. These villains were tough. One was a beholder that constantly emitted a humming noise. Whenever the heroes heard that noise, they ran. So after many sessions of buildup, there was a showdown with the bounty hunters in an abandoned village during a rainstorm. I made the mud a major factor in the battle in part to drive the heroes to fight on the rooftops of the buildings. The roofs could cave in, or catch fire, who knows. All sorts of great stuff. It was a very well-received encounter.
Ship-to-Ship Battles: I love pirates. I love ships. I love running battles where two pirate ships are close together and the bad guys pour onto the ship of the heroes for a huge, chaotic battle. It is always awesome. The thing about ship fights like this, though, is that the heroes always want to claim and sell the enemy ship. You could make it a haunted ship, but you can't do that every time. That was a big problem in the Spelljammer setting. Every ship had a magic helm, and every helm sold for between 40,000 gold and 100,000 gold. The heroes get rich after a single battle!
Web of Chaos: This is from Rogue Mistress, a Stormbringer campaign I converted to 2e. There are these planar webways, tunnels that can take you from one world to another. These tunnels are full of monstrous spiders called Arachnars. You have to pass through the center of the Webway realm, which is between worlds. When you go into that central area.. your body turns inside out. You still move around, you still keep heading for your destination, but you're a humanoid pile of exposed nerves and organs and the massive 40 foot tall mother of the arachnars is none too happy about you trespassing in her domain. I've had groups go through this place two or three times and it is always a heck of a lot of fun.
Zuggtmoy's Throne: This is one I never got to run. It is in the Temple of Elemental Evil, which I tried to convert to 4e but it just didn't work. I was most excited about one of the final rooms, the lair of a demon lord. It wasn't so much about the demon lord, it was about these gems. There's a throne of silver set with 666 precious gems, each worth anywhere from 50 to 5,000 gold. Each stone is attuned to a demon. If the group pries them all free, they "gain demonic attention at a time they least desire it.." 666 demons! I don't literally want to run this encounter exactly like it is, but I feel like there's some really cool variant of this idea that would be great but I haven't figured out what it is, yet. I really like the idea of a demon linked to each gem. Maybe they are trapped in there?
I hope this was helpful. Good luck with your encounter building!
Official .pdf of a list of monsters by challenge rating
Sly Flourish has awesome quick encounter building guidelines here.
The Kobold Fight Club 5e Encounter Builder