5E Lairs

[Jiggy]

So, I've heard a lot of chatter about how cool 5E's "lair" rules are, but all I have is the PHB. Can somebody explain what the lair stuff is, how it works, and maybe give some examples?

[Lorathorn]

Lair rules are similar to legendary monster rules. In that...

A monster may be legendary, and they get special reactions that allow them to act on player's turns.

Lair rules are slightly different, but a monster with lair actions gets an extra action each round (usually on initiative count 20). Lair actions can do things like knocking enemies prone with special effects, causing magma to erupt from the ground, or denying certain targets from healing for the rest of the turn.

It really makes you think twice about fighting monsters in their own lair, if you can help it.

[Jiggy]

So it's more like the lair itself is a combatant, with its own action each round? Or is it like the monster gets an extra action each round, but that action has to be spent doing something that involves the terrain/setting?

[Lorathorn]

The second thing. The monster chooses what happens. Although I could see instances where a lair (a haunt?) might reflect something other than it's monster being involved. That's a good design space, I think.

[Wyntr]

Jiggy wrote:

So it's more like the lair itself is a combatant, with its own action each round? Or is it like the monster gets an extra action each round, but that action has to be spent doing something that involves the terrain/setting?

As Lorathorn said, it is the second. From reading parts of the Monster Manual, it looks like the monster gets to choose from three options once a round - these usually have something to do with the terrain, but it might be something to do with the monster.

For example (off the top of my head for the actual options), a monster might be able to do one of the following once a round on initiative count 20:
* Force creatures in a 10 foot radius to make a Strength save or fall prone (this does not have to be adjacent to the monster).
* Have appendages extend from a 100 foot length of wall; anything adjacent must make a grapple check or be grappled.
* Select a point in the lair that the monster can see; the monster can launch an attack as if the monster were at that point rather than where the monster is physically.

It looks like the options are usually limited so that the same option cannot be selected two rounds in a row; sometimes there is a requirement that all of the options have to be used before they can be reused. Monsters with these lair actions have an increased CR if they are encountered in their lair (the Monster Manual lists the increase for the monsters it gives these actions).

There are also (optional) Regional Effects for a lair. They list two to three ideas for unusual conditions having the lair causes in the area. I'm not sure I'm sold on these - some are subtle, like creatures sometimes feel like they are being watched, or the monster can cast control weather once a day around the lair. On the other hand, it can feel like a giant signpost. "Gee, all the water is polluted and there are overgrowths of plants? I'm sure that's normal." It is atmospheric, but might get to be a giveaway - I'm on the fence about these.

[thenovalord]

Regional effects are steeped in fantasy myth. Desolation of Smaug etc. Everyone knows were a legendary creature lives. Everyone avoids it......well except those silly heroes!

[Lorathorn]

And those boat town people... silly boat townies.