Sanies crouched on a little pirch and told Stormy of the deal
"Here is my proposition, my little monarch. I give you nigh unlimited power, and in return, you conquer Equestria for me"
Stormy gave Sanies a funny look and laughed "Are you serious?! That's all I have to do?! I conquered many lands before and THAT ONE was no different!"
"If it was no different, then why did it lead to your downfall?" Sanies asked in a deadpan tone "Besides, your army did all the hard work while you just sat around and messed about with a stick". Sanies then picked up a familiar staff. Stormy's eyes widen in surprise, then desire. He then tried to grab the staff while screaming "THE STAFF! GIMME GIMME GIMME!!!". After numerous unsuccessful attempts at getting the staff from Sanies' grasp, he collapsed from exhaustion.
"You know, I was once apprentice to Sacanas. He was an ambitious unicorn I promise you that" Sanies said, then he pointed at a broken statue of a cloaked unicorn whose eyes, or rather eye because there was nothing left of the other half of his face, screamed an expression of pain, betrayal and shock "Unfortunately for him, I was more ambitious". Sanies then picked Stormy up by the scruff of his neck.
"As I was saying, I'll give you the power to conquer Equestria all by yourself and you remain in my services for all of eternity"
"Ha! You think you can boss around The Storm King?! That's rich!"
Sanies dropped Stormy to the floor "Fine then, if you want to continue being a slave to the ponies instead of someone that's willing to restore your power, be my guest". Stormy growled at Sanies, then pondered on Sanies' deal.
"FINE! I'll be your humble lapdog or whatever, JUST GIVE ME THE POWER!"
"I knew you would listen to reason, but there is a catch"
"I DON'T CARE, GIMME THE POWAAH!!!"
"The catch is if you fail to defeat the Elements of Harmony and bring them to me, you will be taking their place for a spell I've been practicing"
"The what?"
"The 'cute little ponies' that defeated you the first time, with some help from your former commander Tempest Shadow"
"Yeah, don't remind me"
"Do not worry, I tend to betray people before they have the chance to do the same to me. Only difference being I tend to petrify my enemies and destroy their petrified forms before they have the chance to turn my allies, and soon-to-be traitors, against me"
Sanies then grabs a dark purple pendant-shaped device. "This was from a dimension where I got this version of Celestia" he said as he pointed to a petrified Celestia. "You know, she didn't look like that when I captured her"
Stormy looked at the statue and had one question on his mind, which he would have asked if Sanies didn't interrupt him before he had the chance to speak.
"Why don't I use the doppelganger to take over Equestria? Because if our Celestia found out about her existence, I would be banished to Tarturus again. And trust me when I say our Celestia is far more powerful than this pretender"
Sanies handed the device over to Stormy "This was intended to be used to detect magic readings, but since their world has limited knowledge on how magic works, it absorbed the magic instead. Once you have absorbed enough magic and released it, you will take on a very powerful form capable of destroying the world"
"Uh huh, there's just one problem with that"
"What?"
"How can I conquer Equestria if this thing DESTROYS IT INSTEAD?!"
"Well, you never considered how using the princesses' magic would destroy all of Equestria while you were childishly fiddling with the Staff of Sacanas, so I'm sure using destructive power to rule the world would more than work in your favour"
Stormy fiddled around with the magical device, attempting to figure out how to unleash the magic Sanies was talking about. Sanies just gave a face palm, wondering how in Tartarus did this buffoon manage to conquer so many lands, including Equestria, without one of his underlings successfully usurping him. He then snatched the device away from Stormy.
"Hey, what gives?!"
"In case you weren't listening, this device requires you to ABSORB magic before unleashing it"
"Uh huh, but it doesn't appear to be absorbing anything"
"That's because I have prevented it from absorbing my magic, which if you bothered listening, I'm storing up for a spell"
"So where am I going to get this magic then?"
"Considering Celestia was merciful enough to give you a second chance, I'd suggest you continue attending that School of Friendship everyone was talking about"
"Well, if that's the case, how do I..."
Before he could say anymore, Sanies knocked Stormy out and teleported him back to the school. Sanies chuckled to himself a little bit while looking at the Celestia statue. "Celestia being merciful? I know she has lightened up ever since banishing her sister, but she is not that forgiving" he said as he chuckled some more.