Last Updated on January 22, 2023
Some creatures in DnD 5e represent a threat an order of magnitude greater than those lesser beasts an adventurer might face. These are legendary creatures and they get additional advantages in combat as befits creatures of their status; legendary actions and lair actions.
In this guide, we will go over exactly how legendary and lair actions work and some examples of how you can use these special actions to help make your boss battles feel more climactic and dangerous.
How to Use Legendary and Lair Actions
The first thing to understand about legendary and lair actions is that only legendary actions are actually “actions”. Lair actions are like effects created by the lair and occupy their own place on the initiative order.
Confused? Don’t worry, it will all be clear soon.
Legendary Actions
A creature that has achieved legendary status, like an ancient dragon or a monster from the dawn of time, gets a number of legendary actions to use each round.
These vary between creatures, but most commonly legendary creatures get 3 legendary actions. This number is reset at the beginning of their turn; legendary actions can’t be saved up for later and if you don’t use all of them the extras are wasted.
What makes legendary actions different from normal actions is that they can be used outside of the creature’s turn. Legendary actions always take place directly after a player’s turn in combat, and a creature can only act once between players’ turns.
This limitation prevents legendary creatures from taking advantage of temporary poor positioning by using all their legendary actions at the worst moment.
For each creature, there is a set list of actions that can be used with legendary actions. Some of the more powerful options on this list can also cost more than one “action”, depleting a monster’s legendary actions that round faster than normal.
If a creature can’t take normal actions, for example when it is incapacitated, it can’t take legendary actions. It also can’t use legendary actions until after its first turn in combat if it is surprised.
Lair Actions
Lair actions as mentioned previously aren’t really actions a creature takes, however, a creature can only make use of lair actions if it’s, well, inside its lair!
Lair actions represent the (usually) magical augmentations of a creature’s lair that give it a home-field advantage against intruding adventurers.
A creature without a long-term lair probably won’t have lair actions, which is something to keep in mind if you decide to run an ancient dragon that’s only had its home for a few days.
Lair actions always take place on an initiative count of 20. That means the effect occurs before any players who rolled a 19 for initiative, and after any players who rolled a 20 or higher with bonuses.
Creatures can’t use the same lair action twice in a row, as the DM you’ll have to mix it up rather than simply picking the best option for a given situation.
Lastly, only legendary creatures get lair actions. If, as a DM, you want to give other creatures a way of representing their home field advantage, the lair action system is a great place to start. These would be homebrew however, lair actions are intended to be reserved for the toughest of challenges.
Creatures With Legendary and Lair Actions
Below are some examples of creatures with legendary and lair actions taken from the basic rules PDF.
| Creature | Description | Legendary Action? | Lair Action? |
| Aboleth (CR 10) | A resentful creature from before the gods that can never truly die. | ✓ | ✓ |
| Androsphinx (CR 17) | A guardian of secrets the Androsphinx sees true and rewards valor. | ✓ | ✓ |
| Dragons(Various CR) | Ancient, driven by greed or a quest for knowledge, these beings are the epitome of strength, danger and intrigue in fantasy worlds. | ✓ | ✓ |
| Gynosphinx (CR 11) | A cunning creature that sees beyond the barriers of the ordinary world, testing the wit of those who dare come before her. | ✓ | ✓ |
| Kraken (CR 23) | The tentacled terror of the depths. | ✓ | ✓ |
| Lich (CR 21) | The classic undead wizard hungry for power. | ✓ | ✓ |
| Mummy Lord (CR 15) | The most powerful of the wrapped undead; those who were kings and queens, high priests and forgotten arch sorcerers. | ✓ | ✓ |
| Solar (CR 21) | Celestial warriors who need only 24 of their number to serve the gods and protect the world against cosmic threats. | ✓ | ✗ |
| Tarrasque (CR 30) | An almost unkillable immortal engine of destruction that rises every few decades to feed. | ✓ | ✗ |
| Unicorn (CR 5) | Divine guardians of their enchanted woods. | ✓ | ✗ |
| Vampire (CR 13) | The classic bloodsucking undead; aristocratic, clever, and ruthless. | ✓ | ✗ |
Examples of Legendary and Lair Actions in Combat
Below are two examples of how to run legendary and lair actions. The party is level 10 and consists of a Rogue, Cleric, Wizard, and Fighter.
The combat is run on actual rolls, though I edited these out to keep things simple.
Young Green Dragon
While a green dragon does not have legendary actions until it reaches adulthood, let’s look specifically at its lair actions.
On the side of the forest-covered mountain is the entrance to the green dragon’s lair. The entrance is obscured from most angles by ferns, but the Rogue managed to spot it anyway.
The party ventures inside, and immediately come across the young green dragon that had been listening to them tramp around its lair for the past 5 minutes.
The Rogue goes first, moving forward to attack and then disengaging.
Then, even though it’s not his turn, the dragon is able to use one of its lair actions. In this case, sending tendrils of plant life writhing towards the Rogue with ill intent.
The text for this lair action reads:
Grasping roots and vines erupt in a 20-foot radius centered on a point on the ground that the dragon can see within 120 feet of it. That area becomes difficult terrain, and each creature there must succeed on a DC 15 Strength saving throw or be restrained by the roots and vines.
A creature can be freed if it or another creature takes an action to make a DC 15 Strength check and succeeds. The roots and vines wilt away when the dragon uses this lair action again or when the dragon dies.
The Rogue rolls a 17, making the save but becoming stuck in the center of the area of difficult terrain.
The Cleric then casts Flame Strike, and moves forward and to the side, spreading out around the dragon.
Then the Wizard follows suit, moving forward and casting Cone of Cold.
The fighter stays back, nocking two arrows and making her attacks.
Lastly, the dragon goes, deploying its breath weapon against the Cleric and Rogue.
In the next round, the Rogue is able to move out of the vines and attack the dragon with his cunning action. He isn’t able to retreat as far, however, and takes an opportunity attack from the dragon.
The dragon, realizing it’s facing a coordinated frontal assault and seeing the Rogue has escaped its vines, decides to use its second lair action. This action is defensive, rapidly growing plant life around the dragon into a wall of thorns which blocks it from view.
Note that since this is a new lair action, the vines from the previous round will wilt away and that area will no longer be difficult terrain.
The text for this action reads:
A wall of tangled brush bristling with thorns springs into existence on a solid surface within 120 feet of the dragon. The wall is up to 60 feet long, 10 feet high, and 5 feet thick, and it blocks line of sight. When the wall appears, each creature in its area must make a DC 15 Dexterity saving throw.
A creature that fails the save takes 18 (4d8) piercing damage and is pushed 5 feet out of the wall’s space, appearing on whichever side of the wall it wants. A creature can move through the wall, albeit slowly and painfully.
For every 1 foot a creature travels through the wall, it must spend 4 feet of movement. Furthermore, a creature in the wall’s space must make a DC 15 Dexterity saving throw once each round it’s in contact with the wall, taking 18 (4d8) piercing damage on a failed save, or half as much damage on a successful one.
Each 10-foot section of wall has AC 5, 15 hit points, vulnerability to fire damage, resistance to bludgeoning and piercing damage, and immunity to psychic damage. The wall sinks back into the ground when the dragon uses this lair action again or when the dragon dies.
The Rogue, Cleric, and Wizard are all forced to make Dexterity saving throws and can no longer see the dragon as a wall of thorns bisects the lair, forcing the party to one side and keeping the dragon on the other.
Since the party is level 10 and the dragon is only CR 8, it might use this opportunity provided by the thorns to flee the lair, or, if your DM has decided the dragon is particularly clever, to try to collapse the entrance to the lair from the outside, trapping the party within.
The dragon could also have chosen to create a magical fog with a chance of charming one of the players.
The text for that reads:
Magical fog billows around one creature the dragon can see within 120 feet of it. The creature must succeed on a DC 15 Wisdom saving throw or be charmed by the dragon until initiative count 20 on the next round.
However, since there were four attackers, this was likely to be less effective than the thorn wall, which provides the dragon with cover and more options than trading blows with a stronger party.
As you can see, the lair options allowed a creature ostensibly weaker than the party to create additional advantages for itself. In addition, the lair actions were themed to the environment and the creature in question.
This gives DMs the opportunity to provide rich descriptions if they so wish, and makes the dragon feel more like the powerful entity of magic it is rather than an overblown beast with claws and some poison features.
Aboleth
An Aboleth represents a stronger threat to the party. At CR 10 not only is it a tougher combatant it also has 3 legendary actions:
- Detect: The aboleth makes a Wisdom (Perception) check.
- Tail Swipe: The aboleth makes one tail attack.
- Psychic Drain (Costs 2 Actions): One creature charmed by the aboleth takes 10 (3d6) psychic damage, and the aboleth regains hit points equal to the damage the creature takes.
The party enters a large chamber mostly filled with water. The shores of this underground lake stretch almost to the edges of the cavern leaving about 20-40 feet of land between the water and the walls.
While it isn’t possible to see the depth of the center of the lake, the edges are shallow water and only a few feet deep. The party ventures in, needing to refill their water supply but cautious of threats.
When they get within 10 feet of the water they notice a shape resting in the shallows. The aboleth rears its head and bellows.
The Rogue goes first, running forward and attacking the aboleth that lurks in the shallows. The aboleth’s Mucous Cloud triggers a save which the rogue fails. He is now diseased and can only breathe in water.
The aboleth then takes its first legendary action of the round, hitting the rogue with its tail.
Then its lair action goes off, and the party must make saving throws or be pulled into the water with the aboleth.
The text for this action reads:
Pools of water within 90 feet of the aboleth surge outward in a grasping tide. Any creature on the ground within 20 feet of such a pool must succeed on a DC 14 Strength saving throw or be pulled up to 20 feet into the water and knocked prone. The aboleth can’t use this lair action again until it has used a different one.
The Fighter, Wizard, Cleric, and Rogue fail their saves and are pulled into the water beside the aboleth falling prone.
Then it’s the aboleth’s actual turn. It uses its Enslave feature on the Rogue, forcing a DC 14 Wisdom saving throw against being charmed. The Rogue fails, can no longer take reactions, and is under the aboleth’s control.
The Cleric stands up and moves away from the aboleth, casting Lesser Restoration on the Rogue. This cures him of the disease but does not remove the charm effect.
The Wizard casts Fly on the Fighter so they can stay out of range of the water.
The Fighter stands up, flys into the air, and fires four arrows at the aboleth using their Action Surge feature.
Normally, the round would end here. However, the aboleth uses its remaining two legendary actions to use Psychic Drain on the Rogue to heal some of the damage the fighter and Rogue dealt. The Rogue gets another saving throw against being charmed but fails.
In the second round, the Rogue is compelled to attack the Wizard.
The aboleth uses a legendary action to attack the Wizard with its tail. The wizard fails his concentration check and the Fighter falls into the water.
Then the aboleth gets to use another lair action. Since the entire party is in the water, it decides to deal some additional damage by channeling its power through the lake.
The text of the ability reads:
Water in the aboleth’s lair magically becomes a conduit for the creature’s rage. The aboleth can target any number of creatures it can see in such water within 90 feet of it.
A target must succeed on a DC 14 Wisdom saving throw or take 7 (2d6) psychic damage. The aboleth can’t use this lair action again until it has used a different one.
The Wizard and Fighter both succeed, but the Cleric does not.
Now the aboleth can take its turn. It might choose to simply attack the adventurers who are now within easy reach of its melee attacks, or try to Enslave a second player like the Wizard or Fighter.
The aboleth could also use its third lair option on the following round, which allows it to cast the spell Phantasmal Force with no components on a single creature.
Either way, it’s clear that the fight has turned nasty for the adventuring party. Unprepared to fight the aboleth in its lair, what should have been a reasonable challenge rating has instead become a desperate struggle for survival against their own Rogue and an aberration with plenty of hitpoints to spare.
By using its legendary and lair actions to accentuate its watery advantages and make its other abilities more effective (by draining health from the Rogue to heal itself), this CR 10 monster clearly earns its legendary status.
Going Forward
Legendary and Lair actions are an essential tool for DMs to make fights not only more challenging but also more interesting.
Simply trading weapon attacks and spells until someone dies can sometimes get a little boring; lair actions allow the environment to have an important effect on combat and lair actions add an additional element of danger to these battles.
Next time your players face a monster, pick one with legendary and lair actions and see how they fare!
Growing up I spent most of my time reading, so when I first started playing RPGs in middle school and got a copy of DnD 3.5’s rules I loved their collaborative take on storytelling. These days I like to use RPGs to develop my creative problem-solving skills as well.
