Twitter doesn't help, Jeremy's too busy ignoring WotC's research because it's inconvenient for him to answer questions, so to the forums it is!
The Faerie Dragon has a feature, Superior Invisibility, that allows it to turn invisible as a bonus action. According to the DMG, this feature increases it's effective AC by 2. And nothing else.
Compare this with Nimble Escape, which allows a creature to hide as a bonus action. According to the DMG, this feature increases the monster's effective AC and attack bonus by 4.
What the F-?
The Faerie Dragon has a feature, Superior Invisibility, that allows it to turn invisible as a bonus action. According to the DMG, this feature increases it's effective AC by 2. And nothing else.
Compare this with Nimble Escape, which allows a creature to hide as a bonus action. According to the DMG, this feature increases the monster's effective AC and attack bonus by 4.
What the F-?