The new Monster Manual boasts over 500 creatures, including legendary beings so powerful they can shape the world around them. From a new terrifying hag to the classic retinue of dragons, these creatures can establish lairs—places of power that infuse the environment with their essence. When it comes time for heroic adventurers to confront these monsters in their lairs, it can make for exceedingly epic encounters.

Let's take a look at how these lairs work and how we can flesh out an Arch-hag's lair with the help of the new Core Rulebooks!

• How Do Lairs Work?
• Fleshing Out an Arch-hag's Lair

How Do Lairs Work?

Artist: Martin Mottet

While many creatures—from a group of goblins to an army of fire giants—might claim a cave or ruin as their stronghold, only certain beings are mighty enough to transform their lair into an extension of their power, amplifying their abilities and warping the region around them.

In the new Monster Manual, creatures with this capability have a dedicated lair section in their entry. This overview of the creature's lair provides examples of where it might be located and descriptions of how its presence alters the region. These creatures might also have notes in their stat block that indicate ways in which the monster is more powerful when characters face it in its lair.

Where's the Lair?

The first part of a creature's lair overview offers inspiration for choosing its location. You can use this in conjunction with the creature's habitat entry to narrow down where the creature might set up shop.

This also helps you stock the environment around the lair, as we explore further on in this article.

Regional Effects

Lairs of legendary creatures can impose unique regional effects on the surrounding area that reflect the creature's power. This could be anything from altered weather, to sinkholes and other environmental changes, to even supernatural phenomena like precognitive fog.

Sometimes, regional effects affect all creatures within a certain distance of the lair. Other times, they only trigger when a creature takes a specific action, like drinking tainted water or finishing a Long Rest within 1 mile of the lair. A few regional effects allow the lair's owner to create an effect or cast a certain spell, often with powerful alterations, while in the lair. Negative effects don't often affect the lair's owner and their allies.

When a creature with a lair is destroyed or it moves its lair elsewhere, the regional effects associated with their lair end immediately.

Potent Power-Ups

Some creatures with a lair can access more uses of Legendary Actions or Legendary Resistances while in their lair. These additional resources make the creatures harder to defeat in their lair, so these creatures have an increased XP value when confronted in the lair.

Fleshing Out an Arch-hag's Lair

Artist: Dario Jelusic

The new Monster Manual gives you all the tools necessary to run an epic encounter in a legendary creature's lair. Just crack open your creature's entry, read over the regional effects and stat block, and you're ready to go.

But, if you want to expand upon your encounter to include minions, some exploration leading up to the lair, and a reward for the characters once they finish the fight, everything you need is available in the new Core Rulebooks.

In this section, we'll show you how to prepare for a thrilling showdown with one of the Monster Manual's new high-level threats: the Arch-hag.

Make Sure Your XP Budget is Balanced

The 2024 Dungeon Master's Guide introduces updated rules for encounter difficulty based on the party's level and the XP value of creatures. For a detailed breakdown of the calculations, check out our article on combat encounters.

In this article, we jump straight into applying those guidelines.

Muster Your Arch-hag's Forces

Artist: Helge C. Balzer

Most monster listings in the new Monster Manual have a habitat entry that helps you stock your adventure environments and encounters. The Arch-hag entry suggests it can be found in any habitat, so we'll keep it classic and choose a swamp environment for our hag's lair.

Now, we can use the Swamp Monsters and Any Habitat Monsters lists in Appendix B of the Monster Manual to fill in our hag's entourage.

Arch-hags often form covens, which can also provide some inspiration for picking out our monster's minions. While Green Hags (CR 3) are thematic, they might be too fragile for an encounter with high-level characters.

In the table below, we reskin a Noble Prodigy (CR 10) from the Any Habitat list to round out the second and third hags of our hag's coven when facing off against higher-level characters. All we have to do is change their creature type to Fey and add the Fey Ancestry trait (see chapter 3 of the new Dungeon Master's Guide for more advice on customizing creatures), and we're ready for some toil and trouble!

Lair Encounters Based on Character Level

The table below provides example encounters for an Arch-hag's lair using monsters from the aforementioned lists.

Example Arch-hag Encounters

Create an Exciting Environment

Artist: Brian Valeza

The fight in the hag's lair might be a final, climatic showdown, but that doesn't mean the journey there is simple. Drawing inspiration from classic fantasy tales, let's flesh out the nasty bog our hag has set up shop in.

Let's place our hag's home deep within the swamp, in a remote location surrounded by hazards to ward off potential intruders. The Dungeon Master’s Guide is an indispensable source of inspiration when it comes time to stock the environment around a legendary creature’s lair with all sorts of nasty surprises, especially Chapter 3: The DM's Toolbox.

Scanning through this chapter, we can pick out some non-monster hazards that might be awaiting unwitting adventurers on their way to the hag's lair, such as poisonous gas, fireball fungus, and vicious vine. We can also find rules for heavy precipitation, which makes the swamp more difficult to navigate by giving the characters Disadvantage on Wisdom (Perception) checks.

Our hag might be especially clever and position their lair over a day's journey from the nearest settlement, forcing those attempting to reach the lair to contend with the area's regional effects:

Lapsus Linguae. Creatures (excluding the hag and its allies) within 1 mile of the lair subtract 1d10 from any ability checks they make when they take the Influence action.

Meddlesome Magic. Whenever a creature other than the hag or its allies finishes a Long Rest while within 1 mile of the lair, the next time that creature casts a spell using a spell slot, it also casts Confusion centered on itself. The spell uses the creature's spellcasting ability and doesn't require Concentration.

Random Encounters Leading to the Arch-hag's Lair

Using these hazards and monster listings in Appendix B, we can create a devious list of random encounters for when our party is exploring the region surrounding the legendary creature's lair. While it's entirely optional to do this, random encounters drain the party's resources, establish atmosphere, and help keep the party moving.

In the Arch-hag's Swamp Random Encounters table, you'll find a homebrewed list of random encounters fit for an adventure to our hag's lair. It contains thematic hazards from The DM's Toolbox section of the Dungeon Master's Guide and monsters from the Swamp and Forest habitat lists in the Monster Manual.

For each hour the party spends in the swamp, roll a d6. On a roll of 1, an encounter occurs. To determine what the characters encounter, roll on the Arch-hag's Swamp Random Encounters table. The encounters below are balanced for a party of four level 17-20 characters.

Arch-hag's Swamp Random Encounters

Stock the Treasure Trove

Artist: Ilse Gort

As an incredibly powerful and immortal creature, our hag likely has a hoard of carefully curated magical and mundane treasures in their lair. We can build a hoard fit for such a hag using the row for CR 17+ creatures in the Dungeon Master's Guide's Random Treasure Hoard table, which provides this guideline:

• Monetary Treasure: 6d10 × 10,000 GP (average 330,000 GP)
• Magic Items: 1d6 magic items

Then, we can roll on the random Magic Item Rarities table based on the characters' level (or consult the Magic Items Awarded by Level table). For the example hoard below, we're assuming our characters are level 17-20.

Once we have the number of Rare, Very Rare, or Legendary items our hag's hoard contains, we can roll on the Random Magic Item table that corresponds to the Arch-hag's treasure theme, which is Arcana.

Rolling for our hag's hoard would look something like this:

Random Treasure Hoard table results:

• Monetary Treasure: 320,000 GP
• Random Treasure Hoard: 5 magic items

Magic Item Rarities table results:

• 1 Rare item, 3 Very Rare items, 1 Legendary item

Random magic item results:

• Spell Scroll (level 4 or 5 spell) (Rare)
• Nolzur's Marvelous Pigments (Very Rare)
• Spell Scroll (level 6, 7, or 8 spell) (Very Rare)
• Potion of Vitality (Very Rare)
• Enspelled Staff (level 6, 7, or 8 spell) (Legendary)

Legendary Lairs Await

The lairs in the new Monster Manual are more than just backdrops. They help you create and run epic encounters, whether your players are heading into a stinking swamp to fight a hag or ascending a volcano to square off against a mighty red dragon.

A host of legendary creatures and their lairs are waiting to be discovered, so grab your copy of the new Monster Manual today and prepare to unleash these extraordinary creatures on your players!

Mike Bernier (@arcane_eye) is the founder of Arcane Eye, a site focused on providing useful tips and tricks to all those involved in the world of D&D. Outside of writing for Arcane Eye, Mike spends most of his time playing games, hiking with his partner, and tending the veritable jungle of houseplants that have invaded his house.