[RPG] Do dragons of all sizes get lair actions and regional effects


In my campaign, a black dragon egg was lost by its mother and found by kobolds.

Now the wyrmling is about three years old, holed up in a mine, and being worshipped by the ever-subservient kobolds. Since this dragon is just a baby, I'm not sure if this mine constitutes a lair, or if it's powerful enough to exude lair effects.

My question is "Do dragons of all sizes get lair actions and regional effects?" but a thorough answer will hit all the following points:

  • At what age is a dragon old enough to take lair actions while in its lair?
  • At what age does a dragon's magic expand to the scale of Regional Effects?

Best Answer

Lair actions and regional effects are only permitted to legendary creatures.

From page 11 of the MM:

A Legendary Creature's lair

A legendary creature might have a section describing its lair and the special effects it can create while there, either by act of will or simply by being present. [...] This section only applies to legendary creatures that spend a great deal of time in their lairs and are most likely to be encountered there.

Lair Actions

If a legendary creature has lair actions, it can use them to harness the ambient magic in its lair.

Regional Effects

The mere presence of a legendary creature can have strange and wondrous effects on its environment, as noted in this section.

Since dragon's don't appear to gain their legendary status until they are adults (101+ years old) by reasoning that that's when they also gain legendary actions and resistance, only adult and ancient dragon's gain regional effects and can use lair actions.

This is further backed up, for regional effects at least, by the line:

Regional Effects

The region containing a legendary [insert colour] dragon's lair is warped by the dragon's magic, which creates one or more of the following effects...

under each dragon's description.