It's amazing how much two men could have in common with one another.
Xolarin and Appius Wight. Both were Savants, the second rank of Equites in the Brotherhood.
Both were former Jedi that fell to the Dark Side.
Both were Human and were Taldryanites that transferred in from another Clan.
Both were masters of Niman, the sixth form of lightsaber combat.
And lastly, both men could not stand to be in the same room with one another for more than a few minutes at a time.
I swear Erinyes chose him just to spite me. Appius mused to himself. Next time she can get some other minion to do her dirty work for her!
The Mandalorian liked to think like that, it at least made him feel a little better about his current predicament. The problem was no matter how he looked at it, Erinyes was technically his boss not once, but twice over. Appius was a Quaestor; she was his Consul. He was one of Ciara's Magistrates while Erinyes was the Praetor.
What made the situation even more infuriating was that when the Zeltron gave the order for him and Xolarin to tackle one of the Dark Side infused beasts that now inhabited the remains of the research lab; he had no choice but to comply like the good little Quaestor he was, lest he get on the bad side of the Headmistress too.
He didn't want to do that, he'd heard way too many stories about what happened to those who got on the bad side of the Dark Council.
That redirected him to the current source of his ire, right here and right now. Xolarin.
Force damn it all, why didn't I just kill him on the Matron?
At this moment in time, the Sorcerer was kicking himself for that particular decision. He could have killed Xolarin back then, Proconsul was supposed to be his position for the taking but nooo, it had to go to the artificer of all people, the researcher! Simply because the Taldryan Consul couldn't be frakked to do any of it herself!
Who knows? Maybe here of all places, the Breached Hot Labs on Arx, maybe Xolarin would get himself killed? He wasn't the most combative of people, hence the second reason Appius was here with him in the first place. To be a glorified bodyguard.
"Interesting, it appears this facility has been ripped to shreds, what do you think?" the Taldryan Proconsul joked as he stopped to point out the obviously untold amount of devastation that lay before the two men. Appius barged past him, deciding to completely ignore his fellow Savant's comments.
The facility itself was a complete wreck. The latest war with the Collective was far from kind to the labs due to parts of the Nesolat Platform crashing into the testing rooms and exhibits on the surface, tearing them asunder and leaving who, or rather what, were within exposed to the chaos of the Grand Master's ritual. Some rooms had caught fire, evident by the charred and smoky stench that filled both Human's nostrils as they walked past them. The lights flickered above their head, dimly lighting the way down the wide corridor before disappearing into darkness again.
"Have I done something to upset you, Appius?" Xolarin inquired calmly.
"Yeah," the other Taldryanite answered. "You keep talking. We are here to capture the jotaz. Keep your mouth shut and we will get along just fine."
"Wow, you really hold the Matron against me, don't you?" the Arcanist prodded further.
"The only reason you’re still walking is that I let you live. Remember that," Appius retorted which earned nothing more than a shrug from his fellow Human.
"I don't see what your problem is," Xolarin continued. "My vision was correct, was it not? You turned to the Dark Side, you are wearing Mandalorian armor..."
"Yeah, well jokes on you!" Appius said triumphantly as he grabbed the saberstaff hilt at his side. "These are green, not red. You aren't entirely right!"
Xolarin rolled his eyes.
"You are being childish," the Taldryan Proconsul declared. "I don't want this any more than you. But we need to work together. A brotherhood within a Brotherhood, remember?"
Appius' head snapped towards the Arcanist and through the Force, Xolarin could feel the raw, bubbling anger rise within his fellow Taldryanite.
"Let me make one thing clear," Appius declared, his tone deepening and he pointed a finger at the other armoured man's helmet. "You are not my brother, you never have been and you never will be. I don't trust you, and when the day comes that you slip up I'll be right there, ready to correct the mistake I made on the Matron!"
Appius' voice echoed off the durasteel walls as he finished his speech. Xolarin simply stood there and folded his arms before taking a long, deep breath.
"You know something, Appius? I have tried very hard to be amicable. Believe me, I have. I've shown you nothing but decency since I arrived in Taldryan and yet you've shown me nothing but hostility in return. I get it, you've been told you have a lot of potential. I've seen it for myself and numerous others around the Brotherhood have seen it too. Hell, Ciara probably did when she accepted you as her new Magistrate. But all that got to your head, didn't it? And you just can't accept the fact that I was the one who got the Proconsul position instead of you. That dented your fragile little ego, didn't it? Well, guess what? You're just going to have to accept it. Because despite what you think of me I'm loyal to Taldryan and I have no intention of going anywhere else. Unlike you."
Appius let Xolarin's words wash over him. He had to grit his teeth to stop himself from using the Force to strangle the Arcanist right where he stood.
Suddenly, Xolarin's head snapped towards the end of the corridor, with the Mandalorian following his action very quickly afterwards. What came into view was nothing short of a gargantuan beast. A large, thick creature with bulging forearms and sharp, tusk-like teeth. It stood on its two old oak trunk-sized legs and huffed as it gazed down at the two Force users before it. With a thunderous roar, the jotaz charged towards them with the fury of a vornskr.
Appius reacted by thrusting a hand forward towards Xolarin, sending a pulse of energy into his ribs and sending him careening into the nearby room and out of danger. The Proconsul crashed into a cabinet which sent papers flying in the air around him.
With the Arcanist now out of harm's way for the moment, the Mandalorian turned his attention towards the charging jotaz. The towering beast raised its two fists above its head just as Appius activated his jetpack and leapt out of the way. The gargantuan monster's fists slammed into the durasteel floor and not only dented but cracked and split the floor open. The Sorcerer could have sworn he could feel the vibrations, even in mid-air.
As he landed a few feet down the corridor, the jotaz raised his head and snarled at the Mandalorian, the creature’s pupils dilated as it readied itself for another charge.
You may be strong, but you are definitely stupid! Appius thought to himself. As sparks jittered in-between the fingertips of both his hands. Screw Xolarin, he didn't need his help, Appius could handle this on his own!
Electricity soared and hissed across the gap between the Quaestor and the monster. Unfortunately for Appius, instead of surrounding the jotaz with the agonizing tendrils of lightning, it came to a stop inches away as the beast held out one giant palm in front of it.
The Sorcerer's heart dropped into his gut, he bit his lip behind his visor and took several large steps back as the beast approached him. Banging and slamming into the walls as it did so.
"What the hell did they do to it!?" Appius exclaimed. Whatever had been done to the jotaz, it made it resistant to the Quaestor's use of lightning and he didn't like that. Not. One. Bit.
The Mandalorian readied himself to run before it could charge at him, but before the beast could take another step, the distinct snap-hiss of a lightsaber drew it's attention behind it.
Xolarin stood behind it a few feet away, a green blade humming to his left, unperturbed by the imminent danger this monster exuded. This was his chance to prove himself to the Sorcerer, with his hand outstretched towards the monster, shut his eyes tight and concentrated the will of the Force as a sudden flash of light burst in front of the jotaz.
What Went Well
You set up a strong emotional conflict between Appius and Xolarin on top of the external conflict between those two and the jotaz, which gives the battle extra depth and keeps the reader’s interest while we’re waiting for the fighting to start. You’ve also got a great grasp on the descriptive language in your post. The combat itself was a solid introduction for the rest of the battle.
Room for Growth
The main challenge you had here was with Syntax, particularly with sentence structure (which I covered in your battle with Aiden). You also had a spot where you had an “and” in place of an “as”, at “...his tone deepening and he pointed a finger…”
Suggestions
Purdue OWL’s pages on run-on sentences and sentence fragments apply equally well to this post as they do to your other battle. Beyond that, proofreading (including via resources like Grammarly’s free checker) will help catch errors like the and/as switch.