Richard, meet (and prepare to brutalize) Sombra
Sombra chuckled wickedly at the looks of stunned disbelief on the faces of his crystal slaves... to say nothing of that pink princess, the knight, that meddling little infant dragon, the blade-wielding kirin, that weird green-furred part-kirin part-centaur part-minotaur, and the mildly menacing full-blooded minotaur.
“B…but…but she said-” The Kirin sputtered.
“That the Crystal Heart would just instantly wipe me off the face of your realm? Do you really think I’d keep something that could kill me so easily just lying around at the top of some random tower? Yes, it’s powerful. Hence why I went to such extreme lengths to protect the thing. But that power is nothing in comparison to the power of Sombra, God-King of the Crystal Empire-”
“Slayer of a bunch of nobodies a thousand years dead that no one gives a crap about anymore, tyrant who gets kicks out of tormenting poor, innocent, adorable ponies for shits and giggles, and all-around general asshat.” A voice intoned, cutting Sombra off. The Umbrum’s jaw dropped.
“...who dares…” He growled, his eyes narrowing with fury as they darted around the chamber, scanning it for the source of the voice. But there was no one there besides the motley crew gathered before him, and none of them had spoken; he would have recognized their voice had one of them done so, or at least seen their lips moving. “Show yourself right this instant, or I’ll-”
“Kill you? Good luck with that; I’m already dead.”
And then, there was a flash of ethereal darkness… and then, a sixth creature was in the room, standing in front of the other five. This one was about Sombra's size and shape, and wore a long black cloak with red trimmings, covering everything save the longed, curved horn jutting from the darkness of its hood.
“...an Umbrum?”
“Don’t know what that is, but I do know who I am.” The cloaked pony declared. “I am Richard, Chief Warlock of the Brothers of Darkness, Lord of the Thirteen Hells, Master of the Bones, Emperor of the Black, Lord of the Undead, and the mayor of a little village a hop, skip, and brief dimensional jump away. And I heard much about what you’ve done to the Crystal Ponies during your rule. Which is unfortunate for you, because in tormenting them, you have gained the unique but unenviable privilege of being one of only a select few beings in the entirety of the universe to make me truly, deeply, genuinely angry.”
For a long, long second, there was dead silence.
And then Sombra burst out laughing.
“I-heh-don’t know what strikes me as more stupid;” Sombra admitted, struggling to both breathe and speak in between his bouts of laughter. “that you think you can challenge-heh-me alone, or that you’re doing it for the sake of these whimsical, idiotic ponies.”
Another pregnant pause.
And then, Richard spoke again. "Who said anything about me challenging you alone?" His horn emitted another flash of magical shadows, and the pink princess and knight let loose an ear-piercing scream.
Something else had appeared in the chamber. Something gargantuan in size, only vaguely pony-shaped, easily dwarfing even the minotaur in size. Something formed of bones, darkness, and green witchfire.
Sombra’s eyes went wide, the beginnings of fear forming at the back of his mind. “Wh-what is-”
“In answer to your half-formed question, this is an Eidolon of the Grave. Also known as; every single pony that died, directly or otherwise, at your hooves during your reign.” Richard explained, giving the leg of the massive undead an affectionate pat with one bone-white hoof. “And you’d left all the corpses I needed to throw this bad boy together sitting in a mass grave, completely unwarded and unguarded, their restless spirits free-floating and quite literally praying for someone like me to come along and turn them into something like this so they can get their long-delayed revenge. Now who’s the stupid one?”
Sombra took a slow, trembling step backward, shivering in mortal terror as the massive creature slooowly tilted its head down toward his tiny, frail physical body, its glowing green eyes boring into his soul. “P-p-please, h-have mercy…” He whimpered, too terrified to even register Richard’s insult.
“Wonder how many of your victims asked you to do the same.” Richard responded, his yellow eyes flashing beneath his hood as he stepped forward, “You certainly didn’t. So neither. Will. I.”
“...let me get this straight. This sort of thing,” Shining Armor gestured in the general direction of Sombra’s agonized, horrified screams, “is typical of this pony?”
“The whole “whipping up huge-ass undead constructs” thing? Hell yes.” The strange three(four? five?)-way hybrid responded. “But siccing them on deserving targets, as opposed to, say, the civilians of your “crystal empire”? Not so much.”
“Civilians? What is this pony? A balls-out, unapologetic evil necromancer or something?” Shining Armor inquired further, not entirely sure if he wanted to know the answer.
“A balls out, unapologetic evil warlock. But yeah, aside from the terminology slip-up, you’ve pretty much hit the nail right on the head.” The hybrid responded.
“...and you’re all friends with said balls out, unapologetic evil warlock!?” Cadence exclaimed. “How, exactly?!”
The kirin shrugged. “Far as I can tell? Because he’s bored, and finds our company more entertaining than our deaths.”
“And you’re… okay with that?” Cadance added.
“Not really.” The kirin admitted, his expression becoming slightly downcast. “But then again, who wants to be the one to tell him that we don’t like what he does and he needs to stop?”
Shining Armor cast his gaze across Richard’s three companions; all three were shaking their heads. “Why not?”
“I don’t think you quite understand the consequences of telling someone like Richard “no”.” The grey-furred minotaur interjected. “Allow me to rephrase Cale’s question in terms that better convey the consequences of doing so; who wants to be reduced to a small pile of fine, charcoal-black ash? Or worse?”
Shining Armor glanced at Richard, watching the scene unfolding in front of him with what he was pretty sure was a look of satisfaction. Then at Sombra, still awake, alive, and screaming, despite the fact that the repeated blows from the titanic skeleton the necromancer had summoned had reduced his body to a fine red paste by now. And then back at Richard.
“...that’s a risk I’d rather not take.”
“Smart choice.” The grey minotaur offered.