baby dragon

No they do not get lair actions until they are adult or older.

@Icemiser Where did you read this. There is no mention of this restriction in the Monster Manual. Legendary actions only apply to adult or older but lair actions seem to apply regardless of age.

#2

@tigerlevesque Just like everything in fifth edition, the information you seek is incredibly hard to find. It would have been nice for the designers to write the note about lair actions belonging to adult or older dragons when, you know, they introduce dragons. However, they mention it in the Monster Manual 11. "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. Such a section applies only to a legendary creature that spends a great deal of time in its lair."

@TheDungeonMathster Is your argument that the young dragon is not legendary or that it does not spend a great deal of time in its lair? I think "a great deal of time" is subjective. A young dragon can be up to 100 years old, giving it ample time to spend in its lair.

I am saying that the legendary section would have appeared in the stat block if the designers meant for it to be there; however, their unspoken assertion is that young black dragons are not powerful enough to have lair actions.

Legendary actions and lair actions are two different things.

Legendary actions can be taken on the end of another creature's turn. Lair actions happen at position 20 in the initiative order. a Dragon Wyrmling or Young Dragon doesn't get legendary actions, but they can get lair actions, provided they have a lair of their own.

So, I have literally no clue if I can do this, but my elf sorcerer, who I multiclassed into cleric and warlock has a black obsidian egg-shaped rock, with dark purple flakes on the surface, would actually be a black dragon egg, and he would disappear for a few campaigns and reappear with a young black dragon in tow. Gonna run it by my DM, but first, I wanna know if it's allowed.

@OrsikBattlehammerII I mean there's nothing in the rules that say you can't have a pet dragon as far as I'm aware, it is more will your DM personally allow you to do so. If they say you can have it then yeah as far as I'm aware there are no written rules saying you can't. I would say that would be a Black Dragon Wyrmling not a Young Black Dragon probably assuming you aren't planning to have your character missing for years like 10 years but again that would be up to your DM.

Would anyone recommend this or a wyvern for a bossfight? For a party of 4 lvl 5 characters? 

I used this instead and it was a kickass bossfight.

this will be my pet in my campaign

yes they do, this is made clear in the wording for lair action "the dragon" and in region effects where it refers to a "legendary dragon", This implies ALL dragons get lair actions where as only legendary dragons get regional effects.

we just got TPKed by this sucker.

Quote from ItsMisterReed >>

yes they do, this is made clear in the wording for lair action "the dragon" and in region effects where it refers to a "legendary dragon", This implies ALL dragons get lair actions where as only legendary dragons get regional effects.

 RAW no they don't.  Only Legendary creatures get lair actions. Young Black Dragons don't have Legendary Actions or Legendary Resistances in their statblock, therefore they aren't Legendary creatures and therefore they don't get Lair actions. Not saying a DM can't choose to give them Lair actions, but the design intent was for them to not have them.

Here's Jeremy Crawford on the subject: 

https://www.sageadvice.eu/2018/06/18/do-young-dragons-and-wyrmlings-have-lair-actions-or-regional-effects/

i would say this becasue a wyvern would probaly drop one player in the first round but then a level five party would shread through those hitpoints to fast to be fun for them. While the dragon has the hitpoints to survive a couple rounds if they nova 

if you guys arguing over weather or not this young dragon gets lair actions it doesnt. the stat block it self is for the young black dragon and there is not any mention of lair actions there. vs the description underneath this stat block is for all black dragons as a whole 

Alone? No. It'll get destroyed. However, no dragons are ever "alone". An encounter that I'm building for 5 7th level characters involves layers and using lair actions.

It's set in the underground basement of a castle (I'm running my modified ToD campaign).

Let me describe the layers first.

Black dragon lairs are inundated with scorpions and snakes and insects. So I'll use a couple of giant scorpions and centipedes as well as a few swarms, both insect and snake.

The young black dragons were recently hatched and are being taught by the Cult. 

There are also several black guard drakes around.

Since black dragons are amphibious, there is a huge, contaminated glacial pond that is fed by the nearby swamp. Generally, this is where the dragons will be found. But, in addition to the dragons, there are also several giant crocodiles.

Yes, it looks way OP for my group, but they can handle it and they need to know that.

This will be the final boss fight on this level.

Mean.