Posted by : David Guyll June 21, 2013
One of the traits about legendary creatures is that they can have lairs that not only are capable of independently taking their own actions, but can expand on the out-of-turn actions that the legendary monster can perform. In the example black dragon, the pools of water in its lair could automatically surge forth at a specific initiative count, potentially dragging characters underwater. The dragon also gained the option to spend legendary actions while underwater to heal itself.
This lead to questions about a monster's XP value, specifically as to why it only had one when such a dragon encountered outside of its lair would be at a greater disadvantage than one inside. The column states that they will "probably" present two XP values for encounter-building, but it sounds like it would be pretty a simple matter to just attach an XP value to the lair.
That being said these "lair" rules could be great for handling environments for any kind of creature, and it would be a wasted opportunity to just attach them to legendary creatures: guards armed with crossbows could take shots at you on a catwalk, a planar gate could randomly unleash destructive energies (or vomit forth monsters), and rocks might fall from a ceiling while fighting an earth elemental underground.
There was an article awhile back that talked about making some monsters like the medusa into unique creatures by default. My reaction was one of confusion as Dungeons & Dragons is not particularly known for sticking close to an established mythology, mentioning that gorgons are metallic bulls, basilisks have like, six legs, hydras come in a variety of forms, and depending on your campaign setting minotaurs might be a true-breeding race, blessed cultists, or something else entirely. Really the only unique monster that I am aware of that is not a god is the tarrasque.
As I also said before I think that WotC should focus on interesting, useful monsters and let DMs decide when/if they want to make a monster unique because it is way easier to power up a single monster than to strip away a lot of stuff if you, say, want a nation of monsters. Of course, I also think that they need to bring back elite and solo monsters, because I do not believe that a monster that does not exceed an arbitrary size category need be "legendary" in order to hold its own against a handful of people.
Finally, artifacts. It was briefly mentioned that artifacts could make a creature legendary. While I am fine with this, as there are plenty of instances where a magic item makes someone incredibly powerful, there are also examples of people being capable of seemingly magical feats of awesomeness, and it is disappointing that after 4th Edition made it possible for "mundane" classes to remain viable at any level that to be legendary you either must be made of magic, capable of using magic, and/or have a magic item.