Within the Archenemy set, I noticed the Scheme cards for Nicol Bolas had a lot of redundancy using 3/3 black horror creatures, very similar to the ones already depicted in Horror of the Broken Lands and Grim Strider. Sure, it could be only for the Archenemy set, but if you look, all of the Schemes are set on the world of Amonkhet as far as the art descriptions go, and it seems that it's giving a bit of a spoiler as to what happens when the Hekma is torn down.
Take a look for yourself.
http://magic.wizards.com/en/articles/archive/feature/archenemy-nicol-bolas-preview-2017-06-05
Dunes of Zairo
SHANDALAR
Innistrad - The Darkest Night
~THE RAVNICAN CONSORTIUM~
A Community Set
Commander: Allies & Adversaries