How to Make a Legendary Monster| DM’s Workshop for Dungeons & Dragons Fifth Edition

Hey all!

Thought I might whip up a real quick article today on creating one of the most fun elements of a good Dungeons & Dragons Fifth Edition game: big bad evil guys (aka BBEGs).

This method is pretty simple, too. In fact, it works more or less the same way adding a template to a monster does. Just requires a little bit of thinking on your part.

Let’s dig in.

Step #1 – Pick your base monster.

The easiest way to create a legendary monster is to start with a base monster. This will be the monster that we’ll base the rest of the design on and give us guidelines to what a legendary version of the monster should look like.

For this example, I’m going to pick the Night Hag as my base monster.

Step #2 – If the monster has natural armor, increase its natural armor by +2. If it wears armor, give it the best armor possible.

Natural armor usually scales with bigger, meaner versions of monsters. A +2 bump is a quick and dirty way of scaling up the armor.

If the creature wears armor, then give it the best armor possible (that makes sense with it). Remember that creatures with high Dexterity may completely forego armor or only wear studded.

For those that are already maxed out (like a death knight), you might give it a magic version of the armor. Just make sure that the armor isn’t beyond what your characters should normally receive at their respective level.

So now my Legendary Night Hag has a natural armor of 19.

Step #3 – If the monster has less than 20 hit dice, give it +10 more hit dice. If the monster has more than 20 hit dice give it +5 more hit dice.

The bigger the bad, the more the hit points. Increase its hit points accordingly (but you might wait to calculate it until you finish putting in its new ability scores below).

Step #4 – Increase its best three ability scores by +4 and its other three ability scores by +2.

This is kind of a quick and dirty way of doing this, but it does make for a pretty good rule of thumb. Check out its ability scores and see what its best three scores are. Then, go and increase those ability scores by +4 each. The remaining three scores increase by +2. If there is a tie, select the one that best fits the campaign.

Don’t forget to make adjustments to stats that are affected by ability scores. For example, AC is affected by Dexterity and hit points are affected by Constitution.

My night hag will have the following Ability Scores:

Abilities Str 22 (+6), Dex 17 (+3), Con 20 (+5), Int 18 (+4), Wis 16 (+3), Cha 20 (+4)

This makes her Armor Class 20 and her Hit Points 237 (25d8 + 125).

Step #5 – Give the monster at least three saving throw proficiencies. If it already has three save proficiencies, give it one more.

This one is a little tricky because it’ll require some thinking on your part. But all big bad guys have great saving throws. Therefore, you’ll need to consider which save proficiencies your BBEG has.

Give it at least three. And if its base monster already has three or more, then give it one more.

If it has no save proficiencies already, then give it “the big three”, which are Dexterity Constitution, and Wisdom. This will protect it from a majority of attacks that the characters will lob at it.

Otherwise, consider its biggest weaknesses. If it’s a fiend and has a relatively low Charisma score compared to the rest of its abilities, then buff up its Charisma.

For my night hag, I’m going to give her the big three saves, Dexterity, Constitution, and Wisdom.

Step #6 – Give the monster Legendary Resistance (3/day).

Legendary Resistance is a power that allows the monster to avoid missed saving throws by choosing to pass it instead. This prevents the BBEG from getting one-shotted early on in battle.

Here is the text for the night hag:

Legendary Resistance (3/Day). If the night hag fails a saving throw, it can choose to succeed instead.

Step #7 – Give the monster Multiattack or give it extra attacks for its Multiattack. And give it extra damage for its base attacks, too.

You’re going to want to increase your BBEG’s damage output considerably.

First, if the monster doesn’t have multiattack, give it a multiattack that allows it to make two attacks with its normal default attack.

Second, increase the damage of the base attack. You can do this either by increasing the damage by one die (such as a 2d6 to 3d6) or by adding on a bonus damage type, such as poison (for beasts, monstrosities, and humanoids with weapons), necrotic (for fiends and undead), and so on. Usually, I try not to add more than 4d6 extra damage with the bonus damage type.

Here is how I will have my Legendary Night Hag’s actions:

Multiattack. The night hag makes two melee attacks.

Claws (Hag Form Only). Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 19 (3d8 + 6) slashing damage plus 14 (4d6) necrotic damage.

Step #8 – Give the monster 3 Legendary Actions.

This is another part that requires some thinking on your part, but really, it’s not too bad if you use a few tricks.

Legendary actions allow for a monster to take actions outside of its turn. Typically, the monster will have at least two default legendary action options: move and attack. Then, it will have a third that will cost 2 actions. The third is usually a “crowd control” option, meant to protect itself. The best thing to do here is duplicate the effects of a 5th level or lower spell.

Here is the Legendary Action block for my Legendary Night Hag. I created its Death Sphere action from the spell storm sphere in Xanathar’s Guide to Everything with a few minor tweaks. I thought it sounded metal AF.

Legendary Actions

The night hag can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The night hag regains spent legendary actions at the start of its turn.

Move. The night hag moves up to its speed without provoking attacks of opportunity.

Attack. The night hag makes one claw attack.

Create Death Sphere (Costs 2 Actions). The first time the night hag uses this ability, it creates a 20-foot radius sphere of swirling air centered on a point it can see within 150 feet which remains for 1 minute.  Each creature in the sphere when it appears or that ends its turn there must make a Constitution saving throw or take 2d6 necrotic damage. The sphere’s space is difficult terrain.

Until the effect ends, the night hag can use its bonus action on each of its turns to cause a blast of enervating energy to leap from the center of the sphere toward one creature she chooses within 60 feet of the center. She must make a ranged spell attack (+11 to hit). She has advantage on the attack roll if the target is in the sphere. On a hit, the target takes 4d6 necrotic damage.

Creatures within 30 feet of the sphere have disadvantage on Wisdom (Perception) checks made to listen.

Move Death Sphere (Costs 2 Actions). The night hag can move the death sphere 30 feet.

Step #9 – Calculate the monster’s challenge rating and proficiency bonus.

This is pretty simple to do. The DMG actually gives you guidelines for doing it, too, on page 273.

The night hag has base 237 hit points. She also has legendary resistance, which acts as a 90 hit point bonus. Plus, she’s got resistances, which add a 1.25 multiplier to hit points. So her effective hit points are 408. That makes her a CR 22 on the defensive side… almost. She’s also got a bump in AC from Magic Resistance and having three saving throw proficiencies. So she’s actually a CR 24 creature on the defensive side.

She can deal up to 99 damage per turn with her claws (multiattack and one Legendary Action). Plus, thanks to her death sphere, she can do another 28 damage (catching 2 creatures in it, and hitting another with the enervating bolt). That gives her roughly 127 damage output during her turn, placing her offensive CR at 20.

The average of CR 20 and CR 24 is CR 22. So she’s a CR 22 monster worth 41,000 XP. At CR 22, she has a +7 to her proficiency bonuses. So I’ll need to go back and make adjustments across the board to her skills, saving throws, attacks, and spell DCs.

Here is the final stat block for the legendary night hag:

night-hag

Legendary Night Hag

Medium fiend, neutral evil


Armor Class 20 (natural armor)

Hit Points 237 (25d8 + 125)

Speed 30 ft., fly 30 ft.


Abilities Str 22 (+6), Dex 17 (+3), Con 20 (+5), Int 18 (+4), Wis 16 (+3), Cha 20 (+5)


Saving Throws Dex +10, Con +12, Wis +10

Skills Deception +12, Insight +10, Perception +10, Stealth +10

Damage Immunities cold, fire, necrotic; bludgeoning, piercing, and slashing from nonmagical attacks not made with silvered weapons

Condition Immunities charmed, frightened

Senses truesight 120 ft., passive Perception 20

Languages Abyssal, Common, Infernal, Primordial, telepathy 120 ft.

Challenge 22 (41,000 XP)


Innate Spellcasting. The night hag’s innate spellcasting ability is Charisma (spell save DC 20, +12 to hit with spell attacks). She can innately cast the following spells, requiring no material components:

  • At will: detect magic, magic missile
  • 2/day each: plane shift (self only), ray of enfeeblement, sleep

Magic Resistance. The hag has advantage on saving throws against spells and other magical effects.


Actions

Multiattack. The night hag makes two melee attacks.

Claws (Hag Form Only). Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 19 (3d8 + 6) slashing damage plus 14 (4d6) necrotic damage.

Change Shape. The hag magically polymorphs into a Small or Medium female humanoid, or back into her true form. Her statistics are the same in each form. Any equipment she is wearing or carrying isn’t transformed. She reverts to her true form if she dies.

Etherealness. The hag magically enters the Ethereal Plane from the Material Plane or vice versa. To do so, the hag must have a heartstone in her possession.

Nightmare Haunting (1/day). While on the Ethereal Plane, the hag magically touches a sleeping humanoid on the Material Plane. A protection from evil and good spell cast on the target prevents this contact, as does a magic circle. As long as the contact persists, the target has dreadful visions. If these visions last for at least 1 hour, the target gains no benefit from its rest, and its hit point maximum is reduced by 5 (1d10). If this effect reduces the target’s hit point maximum to 0, the target dies, and if the target was evil, its soul is trapped in the hag’s soul bag. The reduction to the target’s hit point maximum lasts until removed by the greater restoration spell or similar magic.


Legendary Actions

The night hag can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The night hag regains spent legendary actions at the start of its turn.

Move. The night hag moves up to its speed without provoking attacks of opportunity.

Attack. The night hag makes one claw attack.

Create Death Sphere (Costs 2 Actions). The first time the night hag uses this ability, it creates a 20-foot radius sphere of swirling air centered on a point it can see within 150 feet which remains for 1 minute.  Each creature in the sphere when it appears or that ends its turn there must make a Constitution saving throw or take 2d6 necrotic damage. The sphere’s space is difficult terrain.

Until the effect ends, the night hag can use its bonus action on each of its turns to cause a blast of enervating energy to leap from the center of the sphere toward one creature she chooses within 60 feet of the center. She must make a ranged spell attack (+12 to hit). She has advantage on the attack roll if the target is in the sphere. On a hit, the target takes 4d6 necrotic damage.

Creatures within 30 feet of the sphere have disadvantage on Wisdom (Perception) checks made to listen.

Once the night hag creates a death sphere it can’t create another one until it completes a long rest.

Move Death Sphere (Costs 2 Actions). The night hag can move the death sphere 30 feet.

 

Step #10 – Last tweaks based on CR, proficiency, and flavor.

You might have noticed that I made a few more subtle changes to the night hag’s normal stat block.

I switched it damage resistances to immunities. The reason I did this was that as a CR 22 creature, resistances do not create a multiplier for effective hit points. However, immunities do still add a 1.25 modifier. So that was a quick fix instead of having to recalculate the hit points and CR all over again. I also gave her necrotic immunity, which I felt made sense considering her attacks.

Next, I gave the night hag immunity to being frightened. Plus, she picked up a fly speed of 60 ft., true sight, and telepathy.  All of these things are roughly in line with what to expect from high-level fiends and they don’t move the needle too much in terms of CR. I might also add an additional innate spell to give her some middle range abilities, since all of her powers are either long range or close range. Good ideas for that include hold monster, dominate person, and maybe even something like web to slow creatures down. For now, though, I’ll leave it as is.

Note: if you don’t want your legendary creature to be as tough as this one, consider cutting some of these things in half. For example, only award it 5 extra hit dice, give it +2 to 3 stats, only 1 or 2 LRs, etc. Just pick and choose what you want.

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Art by Wizards of the Coast.

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