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Boss Monster Generator — 5e legendary actions & lair lore

A villain built to fight a whole party alone: legendary actions, Legendary Resistance and a lair.

Artwork

Stat block

Actions

Lore

Describe your creature

Try

Challenge rating

Artwork, stat block and lore in about 30 seconds.Free creations join the public Bestiary. Terms.

What is the Boss Monster Generator?

This free boss monster generator builds a legendary 5e villain designed to fight a full party alone. Pick a CR — usually two to four above your party’s level — and you get a stat block with Legendary Resistance (3/Day), three legendary actions, a recharge ability, plus artwork and lore for the lair. Free to use without an account.

Example stat block: The Hollow Regent

A CR 10 undead made with this generator, with every number worked out by the 5e rules.

The Hollow Regent

Medium undead, lawful evil


Armor Class 18 (plate)

Hit Points 187 (22d8 + 88)

Speed 30 ft.


STR

20 (+5)

DEX

12 (+1)

CON

18 (+4)

INT

14 (+2)

WIS

16 (+3)

CHA

20 (+5)


Saving Throws Str +9, Con +8, Wis +7, Cha +9

Skills Athletics +9, Intimidation +9, Perception +7

Damage Resistances necrotic

Damage Immunities poison

Condition Immunities exhaustion, frightened, poisoned

Senses darkvision 120 ft., passive Perception 17

Languages Common and the tongue of its fallen kingdom

Challenge 10 (5,900 XP)

Proficiency Bonus +4


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

Crown of Ash. Undead allies within 30 feet of the Regent can’t be frightened and have advantage on saving throws against effects that turn undead.

Actions

Multiattack. The Regent makes three Greatsword attacks. It can replace one attack with a use of Royal Decree, if available.

Greatsword. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 12 (2d6 + 5) slashing damage plus 9 (2d8) necrotic damage.

Royal Decree (Recharge 5–6). Each creature of the Regent’s choice within 60 feet that can hear it must succeed on a DC 17 Wisdom saving throw or be frightened for 1 minute. A frightened creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Legendary Actions

The Regent 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 Regent regains spent legendary actions at the start of its turn.

Strike. The Regent makes one Greatsword attack.

Rally the Hollow. Each undead ally within 30 feet of the Regent can use its reaction to make one weapon attack.

Ashen Step (Costs 2 Actions). The Regent teleports up to 30 feet to an unoccupied space it can see. Each creature within 5 feet of the space it left must succeed on a DC 16 Constitution saving throw or take 11 (2d10) necrotic damage.

The Regent ruled for the rightful heir until the heir died, and then kept ruling. Its court is a city of ash where every citizen still bows, and its crown is the only thing in the kingdom that is still warm.

Boss Monster design tips

A single monster against four or five characters has a problem: the party gets four or five turns for every one of its turns. Legendary actions fix that by letting the boss act at the end of other creatures’ turns, and Legendary Resistance stops one failed save from ending the fight.

The 5e rule for legendary actions is: the creature can take a set number (usually three) per round, only one at a time, only at the end of another creature’s turn, and it regains them at the start of its own turn. Options typically include a single attack, a movement and a bigger effect that costs two actions.

Describe the villain and their throne room together — “a hollow king who rules an ash-choked court” — and the generator gives you both the fight and the setting.

Give it somewhere to live

The free map generator draws the lair, cave or ruin, with a grid, hazards and a key of locations.

Open the map generator

Frequently Asked Questions

What CR should a boss monster be?

By the 2014 Dungeon Master’s Guide maths, a solo boss against four characters of 5th level or higher is a hard fight at about three CR above the party level and deadly at four above. At levels 1 to 4, one or two above is already hard to deadly. Legendary actions and Legendary Resistance let a single creature hold up at that CR.

How do legendary actions work in 5e?

A legendary creature can take a fixed number of legendary actions, usually three, each round. It uses them one at a time at the end of other creatures’ turns and regains them at the start of its own turn. Some options cost two or three actions.

What does Legendary Resistance do?

Legendary Resistance (3/Day) lets the creature choose to succeed on a saving throw it failed, up to three times a day. It stops a single spell like hold monster ending a boss fight in one round.

Can I add lair actions?

Describe the lair in your prompt and the generator writes lair lore you can turn into lair actions on initiative count 20. Save the boss to your world and ask Lore Assist to expand them.

Is the boss generator free?

Yes. No account is needed for a few free generations a day; sign up free to keep going and save your villain.

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