Messing With Monster Design 2: Instant Monsters

Last time I talked about monster design, it was to discuss variable features in monster design. If you missed that, then I encourage you to read it. This week, I’m going to talk about taking the next step in lazy monster design: Instant Monsters! Just add creativity!

Let’s say, as an example, that you’ve got game on Saturday. That’s tomorrow! You haven’t designed anything yet. You know the basics of the adventure: the players are invading an enemy stronghold, and they’ll be taking on the deadly lionboar clan: a tribe of warriors who train mysterious compound beasts known as lionboars. You take the time to draw out the map of the stronghold, but you still need to populate it with cultists and lionboars.

What EVER will you do?

That Wonderful CR Table

Let’s turn again to page 274 of our Dungeon Master’s Guide, where we find that statistics-by-CR table once more. We know that the cultists are going to be CR 1, lionboars are going to be CR 2, and the lionboar queen will be CR 5.

Now, we could use this table to assemble our monsters piece-by-piece, filling out a complete stat block, but that’s going to take WAY too long. And while the stat block might give us everything we need to know about the enemies in question, this is the only adventure that will actually use them. Therefore, writing up an ENTIRE stat-block for them seems wasteful.

So, instead, let’s design a trio of instant monsters. It’s easy, I’ll show you how!

Step 1: Establish Monster’s Role

First things first, we need to know what your monster’s encounter role is going to be. Are they strikers (high DPS, low defense), tanks (high defense/HP, low offense), skirmishers (middling stats, highly mobile), etc.? For our purposes, we’ll say that the cultists are skirmishers, the lionboars lean toward being strikers, and the queen is a leader. This will help us with step 2…

Step 2: Gather Necessary Statistics

Using the guidelines dictated by our role, we can now look at that table in the DMG and gather the necessary information we need. For each instant monster, you’ll need their Armor Class, Hit Points, Attack Bonus, Damage per Round, and any associated Save DCs, if the creature has a special ability.

For us, the general stats for each creature will look like this:

Lionboar Cultist. AC 13; HP 71-85; ATB +3; DPR 9-14

Lionboar. AC 13; HP 86-100; ATB +3; DPR 15-20

Lionboar Queen. AC 15; HP 131-145; ATB +6; DPR 33-38

However, we need to adjust these things based on their roles. The cultists, for example, are skirmishers, so I want to give them an ability similar to the Goblin’s Nimble Escape. This adds +4 to their effective AC. Therefore, based on the rules set in the DMG, we need to lower the cultist’s hit points by 2 CR levels to compensate. This leaves them with 36-49 hit points, rather than 71-85.

Similarly, the Lionboar is leaning toward being a striker, so I’m going to increase its offensive statistics to CR 3, while lowering its defensive statistics to CR 1 in order to balance it out as a CR 2 creature.

And the Lionboar queen is going to have a Frightful Presence-style ability, which means that its hit points are effectively increased by 25%. This means that its defensive CR needs to be reduced to 3 in order to compensate.

This means that we have our final core stats for each creature.

Lionboar Cultist. AC 13; HP 36-49; ATB +3; DPR 9-14

Lionboar. AC 13; HP 71-85; ATB +4; DPR 21-26

Lionboar Queen. AC 13; HP 101-115; ATB +6; DPR 33-38

This leads us into step 3…

Step 3: The Stat Block

Instant monster stat blocks are very simple, and really just comprise of the statistics above, organized into actual monster-terms. AC and Hit Points turn into solidified numbers, rather than ranges, and Attack Bonuses and Damage Per Round are translated into attacks. In practice, it looks like this.

Monster Name

AC ##; HP ##; Attack +# (## damage type); Special: lorem ipsum.

Now, let’s build that cultist, shall we?

Lionboar Cultist

AC 13; HP 36; Spear or Bow +3 (9 piercing); Skirmisher: Disengage or Dash as bonus action.

And the lionboars:


AC 13; HP 80; Tusk and Claw +4 (11 slashing each); Charge: 20’ charge, +3 dmg, DC 13 Str Save or prone.

Lionboar Queen

AC 13; HP 105; Tusk and Claw +6 (15 slashing each); Charge: 20’ charge, +3 dmg, DC 15 Str Save or prone. Frightening Roar: Action. 30’ radius. DC 15 Wis Save or frightened for 1 minute (save at end of turn to end). Regal Inspiration: Lionboars and cultists within 60’ gain +3 dmg.

by Raquel Gonzales

…And that’s it! Instant monsters! You may note that I didn’t include things like multiattack in these monsters in order to save space. I figured I was able to communicate that using either the word “or” or “and” where I wrote the attacks. So when the cultist’s stat block says Spear or Bow, it means that it can use one or the other, but not both, while the lionboars say Tusk and Claw, implying that you get an attack with each. Maybe it would be easier for you to use different notation, but this is what I find easiest.

You might notice a couple things missing. Like dice, or saving throws, or ability scores. Yeah…let’s talk about that.

The Things Left Unwritten: Assumed Statistics

Do you read Goblin Punch? No? You should really get on that. Arnold K. is one of the brightest minds in the RPG blogosphere. Not only does he do some pretty excellent OSR/rules-agnostic design work, but his homebrew campaign setting is one of the most detailed and intriguing I’ve ever read about. And, let’s be real, the guy writes non-stop. It’s hard for me to keep up with his new work, much less go back into the archives.

Anyway, a while back he wrote an article titled Game Design: When to Write a Rule. It’s a great article, and one of the things I took from it is the idea of “assumed statistics.”

An assumed statistic is a statistic of a creature that doesn’t really need to be written down because you probably know it off the top of your head anyway. The lionboar cultist, for example, is quick and agile, so it probably has a decent (+2-3) dexterity modifier. It’s probably got average Strength, and pretty weak-sauce Intelligence. I don’t really need to write these ability scores, because I know them just by thinking about the creature in question.

Cultists have high dexterity and low intelligence.

Lionboars have high strength and low intelligence.

The lionboar queen has high strength and charisma.

If I ever need them to roll an appropriate ability check (unlikely), I have an idea of what to use, and I can write the bonus down in my notes when it comes up. Until then, it’s an unnecessary statistic that doesn’t belong in the stat block.

But What About Saving Throws?

Something that many would consider necessary is the Saving throw bonus. And my instant monsters have none.

Well, actually, they do. It’s just not readily apparent. See, I kind of view Saving throw bonuses as assumed statistics, just the same as ability scores. A creature is either good, average, or bad at a thing.

If they’re good at a save, then I apply the creature’s Attack Bonus to the saving throw roll. Why? Because the attack bonus is intended to be a combination of the creature’s proficiency bonus and a primary ability score. The exact same as a primary saving throw.

If they’re average, then I apply no benefit and just roll the d20. And if they’re bad, then I apply no benefit and roll the save at disadvantage to reflect a penalty to stats.

See? Easy, right?

And Dice?

If you prefer rolling and adding up dice (I don’t), you can enter dice codes into the stat blocks in place of straight damage (9 becomes 2d8, 11 becomes 3d6, etc.). Admittedly, this does leave out things like adding the creature’s ability score to weapon damage rolls. But it’s a sacrifice I’m willing to make for the sake of simplicity and ease-of-use.

On-the-Fly Monster Generation

Let’s say you sit down to run your game this week. You have your dungeon drawn out. You have your lionboars and your cultists ready to go…

And the players decide to take a left turn at Arseville and journey into the lair of a demon. You don’t have your Monster Manual on you because you had PLANNED to run the lionboars. And your phone only has a 10% charge, so pulling up the SRD is out of the question. What do you do? WHAT DO YOU DO!?

Well, you take that table—that most useful table—and you USE IT!

With what I wrote above, you should be able to create literally ANY monster you need on the fly, without any preparation. If your players want to go chase down the Frost Demon of Winterland, you have all the tools you need right in front of you. Assign it a CR, come up with a couple-few special abilities and get to work.


Look. Instant monsters aren’t going to be for every GM. There’s still going to be people who want to see a full stat block in front of them when they run their game. This technique is not for those GMs. Instant monsters are for those of us who simply want the essentials and literally nothing more.


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