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?