How does the Dark One’s Blessing of the Warlock class apply to multi-kills from an AOE attack?

Can anything see through dragon Changeshape?

I know attacks that require saves don’t double on a criical but…

What level does a Bheur Hag cast Ray of Frost?

If a ghost possesses a magic-user, can it cast spells?

If you have attack and extra attack can you also do a bonus action?