Legendary Actions 5e and Lair Actions for DnD Monsters | CR effect

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Legendary Actions 5e and Lair Actions

Legendary Actions 5e and Lair Actions in D&D

An inherent flaw with D&D 5e is that combat encounters favor the side with more actions per round. It makes planning epic boss encounters difficult to present a fair but challenging fight for your players. Let us deep dive into Legendary Actions 5e and Lair Actions in D&D 

A single boss creature has only one Action per round, while each player has at least 1 per turn. One way of solving this problem is to give your boss some minions to even the odds during the fight. Another way is to give your boss some legendary actions and lair actions.

Legendary actions 5e and lair actions are reserved for epic creatures or boss monsters, but they can be applied to any creature if you do a bit of homebrewing. These actions do basically what their name implies, give your animal a few extra actions per round of combat. That is to help combat some of the issues D&D 5e has with the action economy.

Creatures can use legendary actions to give them more attacks and positioning choices per round. Creatures can only use lair actions when the encounter takes place in their lair or home territory. Let’s dive into each of these mechanics and learn how to use them.

What is a lair action 5e?

A single attack, Action, ability, or spell usually affects a target creature. That could be a charm, sleep, damage, environmental impact (fire, acid, cold, etc.). That’s a lot of ideas of things you can do. Monsters with lair actions are detailed in the MM.

Only one legendary action option can be useful simultaneously and only at the end of another creature’s turn. A creature regains its spent legendary actions at the start of its turn. It can forgo using them, and it can’t use them while incapacitated or otherwise unable to take Action.

Legendary Actions 5e

Legendary Actions 5e Rules from Page 11 of the Monster Manual says the following,

“At the end of another creature’s turn, an animal can use a legendary action. A beast with legendary actions has separate actions it can choose from. Each one costs a different amount of “actions”. Only one legendary action can be used at a time, and the creature cannot use legendary actions while incapacitated. The creature regains its legendary actions at the start of its next turn.”

Mechanics

Creatures have a pool of legendary actions to use from each round of combat. Each legendary Action in 5e dnd can cost between 1-3 legendary actions per use, depending on how powerful they are. Each Action is a clearly defined mechanic and cannot be substituted for something else. These actions could be movement, a defensive manoeuvre, casting a spell or cantrip, using one of the creature’s attacks or abilities, or a special ability only usable as a legendary action.There is no way for a creature to gain extra legendary actions. Once they have expended all of their efforts, the animal must wait for the start of their next turn to regain the use of the feature. Suppose a creature is, for some reason, unable to use its Action. They also cannot use their legendary actions.

The legendary creatures in the Monster Manual all have 3-4 unique legendary actions to choose from. However, per the rules, there is no limit to how many special legendary actions a creature can choose from. You may try to keep it between 3-5 different actions so that it’s simple for me to remember and use, but the sky’s the limit for homebrewing your creatures and actions.

The only rule you have to abide by for homebrewing is that each creature has a set number of legendary actions. Its unique actions should cost several actions depending on how powerful they are.

Legendary actions D&D 5e Kraken

Kraken can use their tentacles and other abilities as legendary actions. Art by KangJason

Action Cost Tiers

There are quite a few creatures in the Monster Manual and other 5e supplements that have legendary actions. Liches are a great example for understanding legendary actions as they have an action for each cost. When creating legendary homebrew actions, consider how powerful each legendary Action is when assigning a price for it.

The one action cost tier consists of actions that are weak attacks or can be used to reposition. Actions such as a weapon attack or a dash action are acceptable for this tier. One unique Action I like to use is a dash that’s half the creature’s speed, but they don’t invoke opportunity attacks.

The two action cost tier is home to the creature’s powerful unique attacks or abilities and CC abilities. Any attack that deals large amounts of damage and can potentially CC the target belongs here. Low to mid-level spells could also be placed in this tier depending on the creature’s spell list.

Powerful, unique, AoE spells and abilities generally cost three legendary actions to use. These actions cause large-scale damage, crippling CC, or a bit of both. A single target ability could cost three legendary actions, but it would have to be an unbelievably powerful ability.

As long as the Action makes thematic sense for the creature, you can slot it in as a legendary action. Don’t be afraid to get creative and add a ton of flavor to your moves. These actions should be powerful and hard to predict. Your players should be forced to change up their usual strategies when dealing with a legendary creature.

Lair actions for 5E D&D monsters 

These are all the lair actions for 5E D&D monsters found in the Basic Rules. I’ll adjust them as needed to make them non-creature specific. There are variations in similar actions. I’ll distinguish the differences with a slash like this: 90/120 feet. Each round on initiative counts 20 (losing all initiative ties). One of these effects takes place:

A spell is cast targeting any number of creatures within 60 feet. If the spell requires concentration, no other lair action 5e can be useful while the spell is in effect. If a target succeeds on the saving throw or the result ends for it, the target is immune to the spell from this lair action for the next 24 hours, although such a creature can choose to be affected.

Pools of water within 90/120 feet of a point on the ground surge outward in a grasping tide. Any creature on the ground within 20 feet of such a pool must succeed on a DC 14/15 Strength saving throw or be pulled up to 20 feet into the water and knocked pronely.

Water in the lair magically becomes a conduit for a creature’s rage. A creature 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.

A cloud of swarming insects fills a 20-foot-radius sphere centred on a point on the ground. The cloud spreads around corners and remains until dismissed (by you, the DM!). The cloud is lightly obscured. Any creature in the cloud, when it appears, must make a DC 15 Constitution saving throw, taking 10 (3d6) piercing damage on a failed save or half as much damage on a successful one. A creature that ends its turn in the cloud takes 10 (3d6) piercing damage.

Magical darkness spreads from a point on the ground, filling a 15-foot-radius sphere until dismissed. The darkness spreads around corners. A creature with darkvision can’t see through this darkness, and non magical light can’t illuminate it. Suppose any of the effect’s area overlaps with an area of light created by a 2nd level or lower spell, the spell that made the light is dispelled.

Part of the ceiling collapses above one creature. The creature must succeed on a DC 15 Dexterity saving throw or take 10 (3d6) bludgeoning damage and be knocked prone and buried. The buried target is restrained and unable to breathe or stand up. A creature can take action to make a DC 10 Strength check, ending the suppressed state with success.

A cloud of sand swirls about in a 20-foot-radius sphere centred on a point on the ground. The cloud spreads around corners. Each creature in the cloud must succeed on a DC 15 Constitution saving throw or be blinded for 1 minute. A creature can repeat the saving throw at the end of each turn, ending its effect on success.

Lightning arcs, forming a 5-foot-wide line between two of the lair’s solid surfaces within 120 feet of each other. Each creature in that line must succeed on a DC 15 Dexterity saving throw or take 10 (3d6) lightning damage.

A strong wind blows around the area from a point on the ground. Each creature within 60 feet of the point must succeed on a DC 15 Strength saving throw or be pushed 15 feet away from the end and knocked pronely. The wind disperses gases and vapours, and unprotected flames are extinguished. Protected flames, such as lanterns, have a 50 percent chance of being wasted.

Fog rises as though the fog cloud spell were cast. The fog lasts until initiative count 20 on the next round.

Thunderclap 5e

A thunderclap originates at a point on the ground. Each creature within a 20-foot radius centred on that point must make a DC 15 Constitution saving throw or take 5 (1d10) thunder damage and be deafened until the end of its next turn.

Stone spikes sprout from the ground in a 20-foot radius centred on a point on the earth. The effect is otherwise identical to the spike growth spell and lasts until dismissed.

A 10-foot-square area on the ground turns into 3-foot-deep mud. Each creature on the ground in that area when the soil appears must succeed on a DC 15 Dexterity saving throw or sink into the earth and become restrained. A creature can take action to attempt a DC 15 Strength check, freeing itself or another creature within its reach and ending the restrained condition on a success. Moving 1 foot in the mud costs 2 feet of movement. On initiative count 20 on the next round, the ground hardens, and the Strength DC to work free increases to 20.

A creature glimpses the future, so it has an advantage on attack rolls, ability checks, and saving throws until the initiative count 20 on the next round.

One creature must succeed on a DC 15 Charisma saving throw or be banished to a dream plane, a different plane of existence imagined into being. To escape, the creature must use its Action to succeed on a DC 15 Charisma check. On a failure, the effect ends on initiative count 20 on the next round. When the product ends, the creature reappears in the space it left or in the nearest unoccupied space if that one is occupied.

Grasping Roots and vines erupt in a 20-foot radius centred on a point on the ground. 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 action to make a DC 15 Strength check and succeeds. The origins and vines wilt away when dismissed.

A wall of tangled brush bristling with thorns springs comes into existence on a solid surface. 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 fence it wants. A creature can move through the wall, albeit slowly and painfully. For every 1 foot, a beast 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 dismissed.

Magical fog billows around one creature. The creature must succeed on a DC 15 Wisdom saving throw or be charmed by a hostile creature within 120 feet until initiative count 20 on the next round.

Magma erupts from a point on the ground, creating a 20-foot-high, 5-foot-radius geyser. Each creature in the geyser’s area must make a DC 15 Dexterity saving throw, taking 21 (6d6) fire damage on a failed to save or half as much damage on a successful one.

A tremor shakes the area in a 60-foot radius. Each creature on the ground in that area must succeed on a DC 15 Dexterity saving throw or be knocked prone.

Volcanic gases form a cloud in a 20-foot-radius sphere centred on a point on the ground. The globe spreads around corners, and its area is lightly obscured. It lasts until initiative count 20 on the next round. Each creature that starts its turn in the cloud must succeed on a DC 13 Constitution saving throw or be poisoned until the end of its turn. While poisoned in this way, a creature is incapacitated.

 

A blisteringly cold wind blows through the area from a point on the ground. Each creature within 120 feet of the point must succeed on a DC 15 Constitution saving throw or take 5 (1d10) cold damage. The wind disperses gases and vapours, and unprotected flames are extinguished. Protected flames, such as lanterns, have a 50 per cent chance of being ruined.

Freezing fog fills a 20-foot-radius sphere centred on a point on the ground. The fog spreads around corners, and its area is heavily obscured. Each creature in the fog, when it appears, must make a DC 10 Constitution saving throw, taking 10 (3d6) cold damage on a failed to save or half as much damage on a successful one. A creature that ends its turn in the fog takes 10 (3d6) cold damage. A wind of at least 20 miles per hour disperses the fog. The fog otherwise lasts until dismissed.

Jagged ice shards fall from the ceiling, striking up to three creatures underneath. Make one ranged attack roll (+7 to hit) against each target. On a hit, the target takes 10 (3d6) piercing damage.

An opaque wall of ice forms on a solid surface. The wall can be up to 30 feet long, 30 feet high, and 1 foot thick. When the wall appears, each creature within its area is pushed 5 feet out of the wall’s space, appearing on whichever side of the fence it wants. Each 10-foot section of the wall has AC 5, 30 hit points, vulnerability to fire damage, and immunity to acid, cold, necrotic, poison, and psychic damage. The wall disappears when dismissed.

Lair Action in 5e dnd

Rules – Page 11 of the Monster Manual

Some legendary creatures and bosses have a special lair or home base. When the players encounter this enemy in their den, they are subject to special conditions called lair actions. At initiative order 20, a creature can use one of its lair action options. They can only use one lair action per round.

It means that the lair “rolls” an automatic 20 for the initiative. No bonuses are applied. So if a player or creature has an initiative roll higher than 20, they’ll go before the lair. Lairs also lose all ties, so any creature that rolls exactly 20 will go before the lair action.

Mechanics

Compared to legendary actions, lair actions are simple to keep track of and use in combat. There are few resources to keep track of, and the only requirement is that the creatures must be within the lair for the actions to affect them.

At the top of the round, you can choose which lair action to use if the creature would like to use one. Generally, the beast has between 2-4 lair actions to choose from at one time.

A creature cannot use the same lair action twice in a row. It helps prevent you from choosing the “optimal” choice every round and keeps the encounter fresh.

D&D 5e Red Dragon Lair Actions

A red dragon’s lair is filled with treasure and in an area known for extreme heat. Credit: WotC.

Design Examples

Lair actions should be useful to raise the stakes of the encounter and help showcase some of the lair’s flavour and flair. These actions are usually extremely powerful.

 

They can be the equivalent of high-level spells or three action legendary actions. Your players are on the creature’s home turf. They should try their hardest to avoid fighting a beast here.

 

These lair actions should either give the creature an advantage in the fight or help slow down or CC their enemies. For example, the gold dragon has both of these options in its two lair actions.

The first lair action gives the creature advantage on all attack rolls, ability checks, and saving throws until its next turn. The second lair action is an AoE that has a chance to banish creatures to a different plane of existence.

Lair actions can also cause damage depending on the lair’s environment. Lairs in biomes with extreme weather or climate can cause damage to the players that aren’t adjusted to the environment. Powerful spellcasters or creatures that set up traps could also have lairs that damage the invaders.

Get creative, and don’t be afraid to make some very powerful lair actions. Be sure to make each lair action have a different mechanic, so the fight stays engaging.

Regional Effects

The lair and the surrounding environment can be changed intentionally by the creature or by the innate magical effects the creature emanates. Regional results end right after the creature dies or will slowly lessen overtime after the creature dies.

Make up a shortlist of regional effects or use the ones in the creature’s respective supplement. Regional effects affect the area in and around the lair and tend to be non-threatening effects that flavour the beast.

Some effects can be useful to the advantage of the creature or players, but most of the time, they’re used to provide flavor and description for the upcoming encounter.

Regional effects are different from lair actions as they do not require any use. You can choose all or none of the impact in the list depending on what you feel makes narrative sense to describe in the game. Be sure to include legendary actions when you are creating epic creatures or bosses for your games. These help even the odds when these creatures are up against a party of 4-5 adventurers.

Lair action 5e helps raise the stakes for the creature and give the party a reason to avoid fighting in its home territory. It also provides the beast with a narrative sense to lure the party to them.

Don’t be afraid to create your lair actions and legendary actions for creatures in the official sources. These different actions are a great way to inject flavour and make encounters more challenging for your party.

As a reminder, legendary actions are completely separate from Legendary Resistance. That is another great tool for helping your epic creatures and bosses feel more powerful, but it is a unique resource from legendary actions. I’ve seen this trip up people new to homebrewing due to its naming convention.

How do legendary and lair actions affect the CR of a creature I am creating in D&D 5E?

You intend to create your monster with legendary and lair actions or consider using a monster without that option and wonder how you adjust their CR.

The short answer for TL/DR: Reduce the CR by 1, maybe 2, for removing legendary actions. Lair actions tend to be weak, so no reduction.

The main reason legendary and lair actions are implemented is that the monster is supposed to be portrayed as a solo threat to the party. Legendary actions, in particular, are designed to offset the tremendous advantage the PCs have with the number of actions they can take compared to their opponent. Lair actions are created, so the monster provides some challenge even before the PCs meet them.

Most of this is unnecessary if the monster is not alone or is not the only threat. If someone goes to Tiamat’s lair and fights only Tiamat, she needs legendary or lair actions. If someone’s going to her lair and also fighting 5 Ancient Dragons (one of each colour, of course), then neither she nor those Ancient Dragons need those additional actions (and would be rather cumbersome for many DMs to run).

Lair actions don’t seem to be all that powerful and mostly provide flavor, and removing them likely changes CR by something far less than a full point (maybe 0,1 or 0,2). Legendary actions tend to change the monster’s power substantially, so I would apply a 10% CR reduction for removing lair actions, or 20% if the abilities seem to be more powerful than their base attacks. Figure the “fractional CR” and round to the nearest whole number at the end.

For instance, if a dragon is CR 18 with lair and legendary actions, reduce by 0.1 for lack of lair options and by 1.8 for lack of legendary actions, arriving at CR 16.1 (rounded to CR 16) without both.

Another example: the Atropal is CR 13 with legendary actions. Its legendary actions are the bulk of its powers, so a 20% reduction is in order. That would place it at CR 10.4, rounded to CR 10. Still a threat, but I’ve seen a cleric nearly one-shot this thing with a level 4 Guiding Bolt critical!