A) King Sombra

The tyrannical ruler of the Crystal Empire

"Binding promises were made on my soul
Grand illusions led astray
Ice cold winds swept my heart away
Bring me back to you..." - Abandoned, by Kamelot

"My crystal slaves..." - King Sombra

Ongoing antagonist

Male

Unknown -- over a thousand years old, though, for sure XD

King Sombra

Slightly taller than the average stallion

Black

Some scars

Bulky, elongated

Grey

Pony

Red

Shadow magic
Can generate black crystals that function as weapons and can neutralize magic.
Invented helmets that utilize mind-control. After being defeated by Celestia and Luna, he discovers how to use this power through his own eyes.
Can turn his body into shadow to dodge attacks and travel long distances (after being defeated by Celestia and Luna).

None

Self-assured
Assertive

Stubborn
Insensitive
Aggressive
Intolerant

Brooding, mostly (LMFAO 😂)

ENTJ

None

Gems, crystals (mostly rubies)

Enslaver of the Crystal Ponies

None

Unknown

After D) Coal was crowned king of the Crystal Empire, he and his queen, C) Nebula, were showered with gifts. One particular gift was a beautiful red gem, presented to the king.
This was, however, no ordinary gem. It was a piece of A) Sombra 's crystal heart, which had been saturated in the dark magic that had seeped into the ground in The Broken Pass, and later harvested from his body.
Sombra possessed Coal, wearing the gem as The Dragon Amulet and later began a transformation meant to restore him to his dragon form. But Nebula shattered the amulet, stopping the transformation.

Moderate

None