Does a spellcaster with lair actions keep them when Shapechanging into an Ancient Metallic Dragon who then uses Change Shape?

Question

A few high-level arcane spellcasting monsters, such as the Lich from the Monster Manual, also have lair actions.

Such spellcasters can prepare then cast Shapechange on themselves to become an Ancient Metallic Dragon (such as a Brass one), while keeping some things:

You retain the benefit of any features from your class, race or other source and can use them, provided that your new form is physically capable of doing so.

It is my understanding that the above would allow the Lich to keep its Lair actions in dragon form.

Such dragons have a special Change Shape ability to transform into a humanoid or beast (such as a rabbit) while keeping certain things:

[...] retains its alignment, hit points, Hit Dice, ability to speak, proficiencies, Legendary resistances, lair actions, and Intelligence, Wisdom and Charisma scores, as well as this action.

It is clear from the Monster Manual's errata that the Lich could not gain the Dragon's lair actions (or the resulting beast/humanoid lair actions, if any):

If a creature assumes the form of a legendary creature, such as through a spell, it doesn't gain that form's legendary actions, lair actions, or regional effects.

But what I'm wondering here is whether the now-twice-transformed creature would retain its initial form's lair actions.

In this example, would the Lich-transformed-into-an-Ancient-Brass-Dragon-transformed-into-a-Rabbit keep its Lich lair actions?

Answer 1

It looks like your lich-dragon-rabbit could use the lich's lair actions still

Shapechange says:

You can't use any legendary actions or lair actions of the new form.

It doesn't say that you lose your currently available lair actions.

In fact, an earlier statement pretty much conclusively allows lair actions to carry over into the new form (as you point out):

You retain the benefit of any features from your class, race or other source and can use them, provided that your new form is physically capable of doing so.

Lair actions are definitely a feature and, given the "other source" clause, it doesn't even matter where the feature comes from. The new form (the dragon in this case) can use the lich's lair action because there is nothing physically making them incapable of doing so and that is the only requirement for them to carry over.

Then, when your dragon uses Change Shape to turn into a rabbit, those lair actions explicitly carry over (again as you point out):

[...] retains its alignment, hit points, Hit Dice, ability to speak, proficiencies, Legendary resistances, lair actions, and Intelligence, Wisdom and Charisma scores, as well as this action.

Thus, as weird as it might seem, your rabbit should be able to use the lich's lair actions. (Which will make for a pretty terrifying rabbit — just watch out for holy hand grenades I guess!)