Sacrificial Altar / Chaos Warpgate

So a few months back, I participated in a monthly terrain building contest on Miniwargaming.com.  The monthly theme was Harmony/Despair.  We were supposed to use that theme to create whatever terrain we wanted, and users would vote on the best representation of the theme.  As I play Chaos primarily, I wanted to build a themed piece of terrain that would look good, and fit my armies.  This was a month or 2 before the new Daemons codex dropped, and I had no idea how fluffy it would end up being totally by coincidence.

As the theme was Harmony/Despair, I wanted to take a piece of terrain that looked completely in harmony with it's surroundings and make it completely turned to the dark side and forever more used only for evil purposes.  It starts with a fairly normal color palette of slate grays and earth tones.  Only the corrupting effects spoil the otherwise mostly natural setting.