Xenonnonex
Hero
Wrong on the count that it came out in 2015? It did.Wrong on both counts: Out of the Abyss is firmly in the Sword Coast region, though, under the Silver Marches.
Wrong on the count that it was not a dedicated campaign setting? It is an adventure book with some sites detailed but it did not detail as much of the Underdark as the 3e Underdark book did.
Wrong on the count that it does not really involve the Sword Coast proper? It does not.