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Instant Monster
The Dungeon Master Experience
Chris Perkins

This regular column is for Dungeon Masters who like to build worlds and campaigns as much as I do. Here I share my experiences as a DM through the lens of Iomandra, my Dungeons & Dragons campaign world. Even though the campaign uses the 4th Edition rules, the topics covered here often transcend editions. Hopefully this series of articles will give you inspiration, ideas, and awesome new ways to menace your players in your home campaigns.

If you’re interested in learning more about the world of Iomandra, check out the wiki.


MONDAY NIGHT. Our heroes are 23rd level, fighting mind flayers aboard an illithid vessel on the Dragon Sea. The mind flayers are tied to one of the campaign’s big story arcs involving a war between the almighty Dragovar Empire (ruled by dragonborn) and the upstart Myrthon Regency, a vassal state of the imperial commonwealth that has declared its independence. It’s a familiar tale with a D&D twist.

Around 11th level, the heroes learned a major campaign secret: The Myrthon Regency was being influenced by mind flayers and other forces from the Far Realm. Knowing that most mind flayers fall in the level 18–20 range (in 4th Edition), my players started getting nervous by the time they reached 16th level. For my part, I’d expected mind flayers to start showing up around 19th or 20th level. As it turns out, through no fault of the players, the Monday night heroes really didn’t get around to fighting their first mind flayers until now.

One of the dangers of running a complex campaign is that it’s easy for the party to become involved in certain unfolding stories and not others. By the time mind flayers were back on the menu, the heroes had gained a bunch of levels. Consequently, the monsters I’d planned for them to fight were now several levels below the party average. Solving this problem demanded special DM ninja skills… and took a lot less time than you might think.

Welcome to the microwave dinner approach to monster design! By the end of this column, you’ll have a new DM superpower: The ability to create a monster of any level “on the fly” in 2 minutes or less.

And by “create,” I mean “customize.” As much as I love creating new monsters from scratch (my favorite D&D activity, in fact, outside of actually running a game), it’s usually unnecessary. Most players sitting on the other side of the DM screen can’t tell the difference between a monster you’ve created from scratch and an existing monster that’s been modified to suit your needs—so you should only create monsters from scratch when you have the time or want to try something weird.

This article presents two simple and effective ways to customize a monster:

  • Take a monster and adjust its level.
  • Turn a monster into another monster of the same level.

The Perkinsian Approach to Adjusting a Monster’s Level

My approach to adjusting a monster’s level isn’t mathematically perfect, but it serves the needs of most DMs. The ultimate goal is to tweak a monster so that it’s level appropriate and doesn’t cause players to shout “WTF!” during the game. This approach has three easy steps.

For each level you add or subtract:

  • Increase or decrease the monster’s defenses and attack bonuses by 1.
  • Increase or decrease the monster’s hit points by 10 (x2 for elites, x4 for solos). If you’re feeling finicky, make that 6 for artillery and lurkers, 8 for controllers, skirmishers, and soldiers. Just remember, this exercise is about easy math, not pinpoint accuracy.
  • Increase or decrease the monster’s damage by 1. If you’re making a minion, its damage is usually around 4 + one-half the monster’s level (minion brutes deal about 25% more damage on top of that).

Don’t bother adjusting the monster’s initiative modifier, skill modifiers, or ability score modifiers unless you’re a stickler for detail; these sorts of changes have little discernible impact on a monster’s combat performance (at least, from the players’ point of view). If the encounter warrants it, increase or decrease these values by 1 for every two levels you add or subtract, and be done with it.

Here’s the dolgaunt monk from the Eberron Campaign Guide, and the dirt-simple level-adjusted version I used in the mind flayer adventure sprung on my players:

Dolgaunt Jailer (use Dolgaunt Monk, Eberron Campaign Guide p.203)
Level 21 Controller
HP 216/108 AC 35, Fort 33, Ref 34, Will 33
+13 to attacks and damage rolls

The Perkinsian Approach to Turning One Monster Into Another

As Jack Burton—er, I mean—Chris Perkins always says, you can’t judge a monster by its level. At least, most players can’t. What makes a monster memorable is its “shtick”—in other words, the one or two powers and/or traits that truly define what the monster does. As long as you’re happy with the monster’s attacks and powers, it doesn’t matter where the rest of its stats came from.

First, find a monster of the role and level you need—preferably one that has at least one attack power or trait worth keeping—and do the following:

  • Give the monster a new name.
  • Ignore any of the monster’s powers or traits that are inappropriate or undesirable.
  • If you’re feeling creative (and only if you’re feeling creative), give the monster a new trait or power—and by “new” I mean something you’ve invented on a whim or something lifted from another critter.

Having trouble finding a monster of the appropriate role and level? Try surfing the “creatures by level” charts at the back of every 4th Edition monster book we’ve ever produced, or better yet, use the D&D Compendium online tool.

I’ll be the first to admit it: This approach to monster customization is the D&D equivalent of stealing someone else’s homework, erasing that person’s name and writing your name on it instead—appropriate behavior for your home campaign only!

Here’s the infernal girallon from the Monster Manual 3, transformed into a foulspawn terrorhulk for my Monday night campaign:

Foulspawn Terrorhulk (use Infernal Girallon, Monster Manual 3 p.103)
Level 22 Brute

Replace the Burning Soul aura with a Psychic Ooze aura (deals psychic damage instead of fire damage, but otherwise identical).

Replace the Burning Ichor power with a Psychic Ichor power (deals psychic damage instead of fire damage, but otherwise identical).

Delete the Combat Climber trait.

The “Two-Fanged Strike” of Monster Customization

If you feel like flexing your DM ninja skills, try using both approaches on one monster. Here’s an example of a monster that I wanted to include aboard my mind flayer ship, but was the wrong level and a bit too complex for my tastes. A dolgrim warrior is basically two goblins fused together, and I wanted my version to be a minion with traits that preserved the monster’s shtick. The traits I ultimately gave the monster were “inspired” by the racial powers of elves and halflings. The end result:

Dolgrim Pest (use Dolgrim Warrior, Eberron Campaign Guide p.203)
Level 21 Minion Skirmisher
HP 1; missed attack deals no damage AC 35, Fort 33, Ref 32, Will 33
+17 to attacks, 13 damage/attack

Replace the Double Actions and Combat Advantage traits with:

Weez Awesome!
Whenever it makes an attack roll, the dolgrim rolls twice and uses the higher result.

Weez Still Alive! (immediate interrupt; at-will)
Trigger: An enemy hits the dolgrim with an attack.
Effect: The triggering enemy must reroll the attack against the dolgrim and use the second roll, even if it’s lower.

I can’t remember the last time I created a custom 4th Edition monster more complex than this.

When you actually sit down to run your customized monster, you’ll need to have a copy of the original stat block handy for reference, and you’ll need a piece of scratch paper on which to write your “adjustments” to the monster. If you’re running multiple customized monsters in an encounter (which I don’t recommend out the gate), consider writing all of your notes on a single piece of paper and using that same page to track the monsters’ hit points.

Lessons Learned

Use your newfound DM superpower freely and often, until it becomes as easy as breathing. Mastery comes quickly—in very little time, you’ll be able to customize monsters “on the fly” while still keeping your players on their toes. The truth is, you should never have to create a monster stat block unless you really want to. Don’t believe me? Take any monster stat block that’s been published and do the following:

  • Write down the monster’s name and a page reference.

  • Make a “short list” of the custom changes you want to make to the monster.

  • Run the monster using the old stat block and your “short list” of notes.

Your players will either believe that you’re running a monster right out of the book, or they’ll think they’re fighting something new. Either way, they’re overjoyed—and you didn’t kill yourself in the process.

Until the next encounter!

—Dungeon Master for Life,
Chris Perkins


Poll #4 Results

Which of the following dramatic storytelling tropes are you most likely to use in your D&D campaign?

  • The heroes discover that a hated villain is actually the pawn or lieutenant of another villain: 20.2%
  • The heroes are betrayed by a trusted benefactor: 14.7%
  • The characters wake up in a prison or asylum, with only their wits to save them: 9.4%
  • The characters travel through time and glimpse the past and/or future: 8.8%
  • A villain returns from the dead to plague the heroes: 8.6%
  • The gods use the characters as hapless pawns in some petty game: 7.0%
  • One or more characters are (rightly or wrongly) declared criminals: 6.7%
  • A character learns that he or she has inherited a family curse or a haunted keep: 4.9%
  • A character discovers that a family member long thought dead is actually alive: 4.1%
  • A character must confront an evil family member: 3.3%
  • The characters go to sleep and wake up in unfamiliar surroundings: 3.1%
  • The characters are trapped in another creature’s dream: 3.0%
  • The characters are killed and turned into undead: 2.0%
  • The characters are transformed into monsters, children, or ant-sized versions of themselves: 1.1%
  • A character is haunted by the ghosts of dead friends or slain enemies: 1.1%
  • The character encounter Elvis Presley or some other real-world celebrity: 1.0%
  • A dark influence changes a character’s alignment to evil: 0.9%

The Dungeon Master Experience: Poll #5

Which version of the Dungeons & Dragons game provided the rules set for your first DM experience?
Original Dungeons & Dragons (“White Box”)
Dungeons & Dragons Basic/Expert Game (“Red Box”/”Blue Box”)
Advanced Dungeons & Dragons 1st Edition (Player’s Handbook et al.)
Advanced Dungeons & Dragons 2nd Edition
Dungeons & Dragons 3rd Edition
Dungeons & Dragons v.3.5
Dungeons & Dragons 4th Edition
I wish I knew!
Which version of the Dungeons & Dragons game provided the rules set for your best DM experience?
Original Dungeons & Dragons (“White Box”)
Dungeons & Dragons Basic/Expert Game (“Red Box”/”Blue Box”)
Advanced Dungeons & Dragons 1st Edition (Player’s Handbook et al.)
Advanced Dungeons & Dragons 2nd Edition
Dungeons & Dragons 3rd Edition
Dungeons & Dragons v.3.5
Dungeons & Dragons 4th Edition
I wish I knew!
Christopher Perkins
Christopher Perkins joined Wizards of the Coast in 1997 as the editor of Dungeon magazine. Today, he’s the senior producer for the Dungeons & Dragons Roleplaying Game and leads the team of designers, developers, and editors who produce D&D RPG products. On Monday and Wednesday nights, he runs a D&D campaign for two different groups of players set in his homegrown world of Iomandra.
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