This design is what my dreams are made of.  
Powerful concept.

After defeating King Sombra and watching the ending, if you return to the Cradle of the Crystal Heart, you can find a new huge spacial distortion that wasn’t there before. The telltale purple miasma of Dark Magic waft out of it, along with a terrible smell, a smell like a great pile of old, smoldering embers.
 
“What in the hay?! Is it just me, or was that thang there not there before?”  
“What a DREADFUL looking portal and that smell is absolutely REVOLTING… Don’t tell me we’re going in there?”  
“Oh my…”  
“Hey, I say let’s do it! I’ve been waitin’ for another good fight ever since we took Sombra down!”  
“I’ve got a BAAAAD feeling about what’s on the other side of that, girls… Don’t you feel it, too? It’s like… all the parties in the world were all stopped, all at once, and for good!”
 
“Pinkie’s right.. I’ve never felt such strong Dark Magic, not even from King Sombra… But when we let the first portal alone, it kept growing… It became even more powerful. And this Dark Magic is the strongest magic I’ve ever sensed right now and the portal’s already huge…!!!”
 
When the portal is approached, you will receive a warning: Through this portal awaits The Absence of the Sun and Moon, the Nothingness That Has Shadowed All Love and Magic, The Darkened Star. Are you sure you want to go through? YES / NO?
 
After the first short introductory cutscene, Shining Armor and Cadance will be standing by the save point. It is highly advised you do any last minute crafting, upgrades and repairs to your equipment now, go ahead and use up all of your Bits and materials, there’s nothing after Solar Flare that you’ll need them for.
 
Oh.
 
And be sure to your game before you go through the portal…

HOLY SyayT this is amazing

ALL MY YES!