Monsters on a Role: Controllers

Tentacles are a highly underrated method of maintaining control

We're nearing the end of our series on monster roles. After this article, all that's left is Leaders, which will kind of play into a conversation about boss monsters in general. But for today, we'll talk about the Controller, one of the most interesting and complex monster roles.

Controllers

What makes a good controller? Well, that's tricky. A controller is a monster that disrupts a PC's plans. But what are those plans? How do we build a monster that stops a group's strategy when the PCs can do anything?

Well, they can do anything, but they usually do certain things that we can anticipate.

As I've been saying in this series, a group of characters usually follows a particular combat pattern. The fighters and tanks run up to the front lines. The casters and bards stay back. The rogues and monks try to find advantageous positions. And they usually find those positions in the first couple rounds of combat, after which they don't move much.

Then, more fairly predictable things happen. The fighters attack. The casters cast. The rogues backstab. The barbarian rages. The cleric buffs. Et cetera, et cetera.

So when you build a controller, you can make a few different kinds.

A simple type of controller is the Movement Controller. Basically, these guys are the most effective in the first couple rounds of combat. While characters are moving around, these monsters destroy the player's ability to follow the pattern they want to.

These can come in a few different varieties. A Movement Controller could freeze a fighter before they get to the front line. Or, they could pull a caster to the front lines. Maybe they have an ability that forces movement, and they use it to push the party's rogue right into the clutches of a Brute monster.

A suplex is acceptable

Another type of movement control is zone control. There are a lot of effects like this, mostly in the domain of Druids and Clerics. Basically, make a certain area bad to stand in, and you force the players to change their strategy. This could be anything from some extra damage to a condition like poison or petrification.

Now, zone control also comes in different flavors, based on who it needs to be affecting. The Spike Growth spell, which deals damage on movement, won't do anything against fighters or casters. But it will certainly lock down a rogue who was going to use their Cunning Action to Disengage with your monster. An area of Darkness can nullify the efforts of casters, but if you place it around fighters or rogues, you'll only succeed in hamstringing your own brutes. Be selective in your application of these effects!

A more complex type of controller is an Action Controller. These types of monsters have effects that trigger when a player character performs a certain type of combat action. You could have a lightning-fast knight that deals opportunity attacks to anyone that takes an attack action within 5 feet of him. You could have a section of the room that shocks anyone taking a reaction. Perhaps those who take a Help action near the Altar of Selfishness take damage. Or maybe you can only take attack, dash, and hide actions in the Domain of the Feral God

Again, these are obviously going to target different classes differently. Rogues and fighters love their bonus actions, while only casters would take the Cast a Spell action. Again, think about the effect you want and how it will impact your group.

Delicious wizard flesh

Finally, we can have Class Controllers, a specialized type of Action Controller. This is a controller purely designed to take down a specific class. There aren't many examples of these in the vanilla Monster Manual, but check out the Chelicerae (Tome of Beasts pg. 54). A monster with Magic resistance, spellcasting, and the ability to drain a caster's spell slots? That's a class controller.

Other Class Controllers would target certain abilities. A Pacifist Golem might prevent barbarians from raging near it. A creature made of liquid blasphemy might prevent the Channel Divinity ability.

For Class Controllers, it's important to know what classes are in your group, and how the player will react to one of their abilities being removed. Will it be a challenge, or a cheap shot? One way to avoid pulling the rug out from under their feet is to make sure the players have the chance to research the monster beforehand and know their abilities will be compromised. Then, it becomes an interesting combat puzzle, instead of a sucker punch.

So, with all these different types of controllers, with so many different abilities, how the heck do we make one?

Let's start with a basic mechanic, since this will likely be a single trait or spell we add to the monster (via innate spellcasting or the like). We begin by asking ourselves some questions about the effect of the trait, and determine its CR impact along the way.

First off, ask who the trait will affect. You can't answer this question without knowing the composition of your party. If you make an ability that targets wizards, and half your party is wizards, then that's going to be a powerful ability.

I've got my eye on you

Next, estimate how much damage the ability will deal over the course of three rounds. Again, this is affected by what the ability is and who it's targeting. If the trait prevents damage of a particular type (for example, by removing attacks or spellcasting), estimate how much of the monster's HP will be saved by the ability. This will effectively increase the monster's HP by that amount.

If the trait prevents movement or pushes combatants far enough away from the monster that they miss a round of fighting, this will generally save 1/4th of the monster's HP, unless the characters are 11th level or higher. This is because of the abilities and spells available to characters at certain levels. At higher levels, character movement is generally overshadowed by damage output at both close and ranged distances.

If a trait pulls a PC into combat (like a monster using Vine Whip to pull a caster into a fight), the effect on HP and damage is negligible.

Finally, we'll need to determine if this trait stems from the monster's Mental abilities or its Physical abilities. You'll see why this is important in a moment. For example, a gargoyle that can cast Fog Cloud would use its mental abilities, but a gargoyle that breathes thick smoke with the same effect as Fog Cloud would use its physical abilities.

So now, let's determine the CR impact based on our equations, then write the ability.

• Damage Increase/decrease per Round / 12 = Increase/decrease in CR 
• Effective HP increase/decrease / 30 = Increase/decrease in CR

From here, applying the formulas is fairly simple. A few notes:

1. If the trait affects more than one creature, double the effective damage/HP adjustment.
2. If the trait creates a zone that can be moved away from, treat its effect as if it only lasts one round
3. If the trait has a minimal effect on a combat (for example, preventing Channel Divinity effects) because the characters can work around it, the CR impact is negligible

As for writing the ability, there is so much variety in monster types and controller types that I can't tell you how to make something that's a good fit for your monster. But I can tell you a couple things about writing abilities and traits in D&D.

When you have an effect that hits the players like this, you have to decide if you want the effect to be avoidable. About 95% of the time, the effect should be avoidable. That means the players get a saving throw to avoid the potential effect.

How do you calculate the DC for a saving throw on a monster trait? Well, remember how we decided whether the ability would be Physical or Mental? Now that comes into play.

Fog: an adventurer's best friend

You likely already know how to calculate a save DC for a player character. 8 + proficiency bonus + relevant ability modifier. And it probably won't surprise you that monsters use the same proficiency bonuses as PCs. But what ability should we use?

Well, that's pretty straightforward. For Physical traits, we use Constitution. For Mental traits, we use Charisma. So the gargoyle that could breathe a Fog Cloud would use Constitution, and the gargoyle that could cast Fog Cloud innately would use Charisma.

There are two exceptions to this rule. First, grappling/constricting/etc always uses Strength. Second if a monster has class levels in a spellcasting class, they use the ability modifier of that class instead (Clerics use Wis, Wizards use Int, etc).

So now we know who to make our save DC, but for nearly every ability, we could make a Physical version and a Mental version. Which one should we use?

Here's why this matters. If we made a gargoyle with a Charisma-based ability, that ability would be pretty weak compared to the Gargoyle's attacks. The save DC would be a measly 8.

You want to try to keep the save DC in line with the monster's CR. This means you want the final DC to be within a couple points of the monster's attack bonus + 9. The gargoyle's attack bonus is + 4, and a Con-based ability would have a DC of 13 for the gargoyle, so it works out much nicer to have the ability be Physical in nature.

With all of that in mind, let's end the article with a couple Kobolds, eh? Kobolds are excellent candidates for controllers for a few reasons. First off, they die easily, meaning they are more effective when they can toy with the players before they snuff it. Second, they have a reputation as trap builders, which lends itself to a good thematic type of controller.

We'll do three: a movement controller, an action controller, and a class controller.

Our movement controller can be the good ol' "Kobold with a Lasso". This won't have an impact on CR since we'd basically be dragging casters and rogues into fighting territory with the Kobold hoard, but let's still figure out how this trait will function.

While in the lasso, make a DC 20 Charisma saving throw or be forced to tell the truth

Since this is a grapple check, the save DC will be based on strength. So, it will be DC 8. But we could include a version of pack tactics in the trait to reflect the Kobolds working together. Finally, we need to determine what ability a target would use to avoid this. I'd say dexterity, to dodge out of the way.

So here's our trait, which would go under "Actions" on the stat block. Again, there's no CR effect.

Lasso. The kobold targets one creature within 30 feet with a thrown lasso. The target must succeed on a DC 8 Dexterity saving throw, rolling with disadvantage if the kobold has an ally within 5 feet of itself. On a failed save, the target is pulled up to 30 feet towards the kobold in a straight line.

Now, let's do an action controller! I like the idea that kobolds build traps that fit on them, often to their own detriment. We'll focus on melee attacks for control.

Basically, this kobold is covered in sacs of pus it gathered from another monster and tied all over itself. If you hit it from within 5 feet, it will splash on you and deal some acid damage.

Now, we don't want to make this Kobold too dangerous, so let's try to make him a CR 1/4. That means the most damage per round we can increase (to raise his CR by 1/8) is 1.5 damage. That's a CR increase of 1/8 multiplied by 12 (the amount of damage it would take to increase the CR by 1).

But once the players realize this, the kobold probably won't get hit again. So, we can say it really only happens for 1 round. That means we can up the damage of the single attack to 4.5, since it will be divided by 3 rounds. Conveniently, the average roll on a d8 is 4.5.

Note that we're making this damage unavoidable. To make this work, the DM will have to make sure the players know this Kobold is covered in sacs of fluid. To emphasize that, let's make this Kobold a little more weighed down that their companions.

With that in mind, here's our ability. The CR of this kobold would be 1/4.

Pus Sac Armor. When the Kobold is hit by a melee attack from a creature within 5 feet, the creature takes 4 (1d8) acid damage. The Kobold has disadvantage on Dexterity saving throws.

Finally, let's do a class controller. I've always pictured Kobolds and dragons as inseparable, so let's target a Dragon Sorcerer. Since this one is kind of specific, let's make this monster a Kobold shaman.

Don't mess with my dragon-god!

Remember, the key to making a good class controller is to make it a combat challenge, not kick a player out of a combat. How can we make things more challenging for a spellcaster?

Well, sorcerers focus on damaging spells, and dragon sorcerers usually focus on a single element as well. So we could say that this kobold shaman creates a zone where, when a spell of that element is cast, the caster takes a certain amount of damage. It could be a set amount, or it could be proportional to the spell cast.

Since this is a major part of a sorcerer's build, let's make this effect avoidable. The DC would only be 9, an easy DC to hit, so we'd also not want the damage to be too great. This should be a hampering ability, not a save-or-die ability, and the sorcerer's d6 hit die is already pretty flimsy. To offset that low DC, we'll make this a wisdom save, which sorcerers lack.

As for the CR effect, let's assume this will affect the sorcerer for one round, and we don't want to increase the kobold's CR beyond 1/4. Again, we have about 4.5 damage to work with, but we can say that the damage will (usually) be less than that based on the proportional nature of the trait.

Here's what I'm talking about:

Servant of Dragonfire. When a creature within 30 feet and hostile to the kobold casts a spell that deals fire damage, the creature must succeed on a DC 9 Wisdom saving throw or take 2 (1d4) fire damage per spell level of the spell cast, or 1 fire damage if the spell was a cantrip. This damage ignores fire resistance.

So, after the first volley of sorcerer attacks, which will probably include Burning Hands or Scorching Ray, the dragon sorcerer will realize their powers are being targeted. After that, they can use some spells they don't normally use, or weigh their more powerful spells against the damage they would take for casting them.

That's all for the Controller. There weren't as many concrete examples in this article, but hopefully you now have the tools to make some cool controllers for your game. This is one of my favorite ways to spice up combat!

Too spicy! WAY TOO SPICY!!

Thanks for reading!