"Petrification magic" Sacanas announced "A very powerful type of magic used when Tartarus is a bit too much for somepony or they could just slither their way through the bars of their cages". Sanies just stared at Sacanas, something that Sacanas noticed and was slowly started to get irritated by.
"What is it, Sanies?"
"Are you going to bust out into another musical number again? Because if you are, I'm going to see if any sorcerers like Grogar and Yaksputin are still alive so I can learn from them......On second thoughts, maybe not Yaksputin. He'd probably sing about something involving stuff happening in the dark of the night"
"I'll have you know that busting out into musical numbers has been an Equestrian tradition for centuries. And even if you don't like singing, I'll have you know that fiendish individuals like us always sing the best songs"
Sanies made a mental note of the things he will not miss once he had destroyed Equestria, but not before taking care of his master. Random musical numbers just made it to the top of the list. While he was thinking to himself, Sacanas handed, or rather hoofed I should say, Sanies an obsidian (and no, it wasn't an Obsidian Orb because those haven't been invented yet) from his drawer. "As you know by now, which is probably why you eat living creatures instead of gems like most dragons do, gems, diamonds, crystals, orbs and other shiny objects can be a source of great power" Sacanas explained "The obsidian is frequently used for seeing the future and moving obstacles out of the way. One day, somepony figured out a way to turn living beings into obsidian via very complicated alchemy, mainly so he can telepathically communicate with whoever that pony petrified and use it as a living crystal ball. I wouldn't be surprised if he got thrown in Tartarus for that, but the point is I'm giving this rock to you in order to increase your magical capabilities".
"And I'm guessing obsidian has something to do with petrifying ponies" Sanies said while holding the obsidian.
"Don't be hasty, my little apprentice. It can be used for a variety of spells such as magic absorption, seeing the future, removing toxins and reading the minds of any mares that take your fancy!" Sacanas excitedly explained, before turning away for a bit with a melancholic expression on his face "Unfortunately, they think you're creepy when you try to do that".
Sanies just yawned and stretched "Yeah, real nice history lesson, but when are we actually going to turn people into stone?"
"Oh, but this spell can only turn ponies and other living creatures into obsidian! The only way you can turn someone into just generic stone with no magical properties to speak of are tricking them into a staring contest with a cockatrice or a gorgon OR using the Elements of Harmony. Tricky thing is no-one ever really knows how those blasted gems work! Believe me, I tried when Celestia was in the middle of a diplomatic meeting involving trade disputes"
"Nobody cares about trade disputes"
"And that's why very little people care about how a war gets started, especially if it's a fictitious war that leads to a dictatorship. And I should know because I read a very popular, and for good reason, work of fiction involving a band of revolutionaries taking down an evil dictatorship. Then they wrote a prequel to that story involving boring trade routes and.....This is getting out of hoof, isn't it?"
Sanies just gave Sacanas a look that says "I wonder what gave you that idea". After noticing his apprentice's growing frustration, which he kept hidden with snide remarks, sarcasm, and eye rolls, Sacanas decided to continue on with the lesson by teleporting a mouse out of thin air. Sanies just gave an exasperated look at the mouse.
"You must be joking"
"Since you are a novice, you must start small"
Sanies sighed, stretched his arms, cracked his neck a few times, breathed in deeply and focused on the mouse. And as he does so, the mouse started to slowly turn into obsidian. It tried to scurry but it found that it couldn't do to his feet slowly becoming all cold and heavy. The feeling went up all away around it's body until it was frozen in a state of terror. While Sanies was annoyed that Sacanas gave him something so small to practice on, he wouldn't deny that the mouse's fear gave him a sense of pleasure. And when he was done, he decided to crush the mouse's petrified form into dust.
"What did you do that for?!"
"What? You should have known by now I have a taste for destruction"