Acting quickly, Mike released the mana he'd been holding, infusing his mind and enhancing his willpower. With the resulting clarity, he did three things simultaneously, straining his concentration to the utmost to do so.
First, he sent a quick mental impulse to Selene, indicating that she should begin her own attack. Second, he activated the magical traps he'd placed in the vicinity of the tunnel entrance, causing the area to erupt in a virtual hellstorm of fire. The twelve runic symbols he'd carved into the ground and charged with his mana each created fireballs that exploded with the force of an anti-tank missile.
Finally, since he knew that those traps probably wouldn't do any lasting damage to the vampires, he took two steps back and conjured a sword with Earth Magic.
It was good that he did, since a claw-like hand encased in a red, glowing aura swept through the space he'd been occupying mere heartbeats ago. Esmerelda's face followed soon after, mouth twisted in another grin. Mike could see a few burned patches of her skin regenerating even as she moved closer, arm held threateningly.
He wasn't sure what kind of attack that might be, but he quickly decided that he wanted no part of it. Falling into a Flowing River stance, he swept his created blade under the girl's arm, deflecting it away while carving into a section of her torso in a spray of blood.
Unsurprisingly, the ancient vampire was unphased by the injury, and continued attacking with her other arm. As she did so, she started laughing. "HAHAHA! That's more like it! I heard you were a warrior as well as a mage! It's been so long since I've had a good fight. Try not to disappoint me!"
[Why do all of my enemies want to banter in the middle of fights?] He thought while infusing Water Magic into his sword style. A swirling nimbus of clear liquid surrounded the blade of his sword as he stepped into the vampire's range.
With a slow and effortless movement, he slipped past his enemy. A metallic ring filled the air as he did so. For a moment there did not appear to be any cause for such a sound, but soon Esmerelda's left arm fell to the ground neatly severed at the shoulder.
The vampire looked down at it for a second, still grinning and muttered. "It's been awhile since I've seen someone use Almiran swordsmanship. Not bad, but I hope you don't think that will be enough to stop me."
Tendrils of blood extended from the stump of her arm and attached themselves to the rest of her limb, before quickly retracting with a slurping noise that was the most disturbing part of the entire process.
Sighing, he raised his sword again, preparing for the next attack. "I assumed that it would have little effect on you, but I was interested in testing the limits of your regeneration. Tell me, did you simply reattach your arm as a means of more fully demonstrating your healing capacity to demoralize me, or are the mana requirements for a complete regrowth too draining for you to use it while still playing around?"
For the first time since the start of the fight, the girl showed a flicker of disconcertion, little more than a momentary tightening of the eyes, but Mike had been watching for it.
[Alright, that confirms it. Her regeneration works like mine. She can heal from pretty much anything so long as she has the mana for it, but once that's exhausted…]
Meanwhile, Selene was chasing the other vampire who was retreating while firing his rifle. The former Vargulf had so far managed to dodge the worst of these volleys, and deflect the rest with her staff, but Mike could see a few grazes had left their mark. She was taking a dangerous course of action, but he suspected that she had no other choice.
[I'm not sure how strong she is, but I doubt she's going to be able to do much more than buy time against an enemy like that.]
"Clever, but don't think that will be enough to beat me." Esmerelda replied, stealing back Mike's attention. "I've read the reports on your fights up to this point. Hells, I've even seen a few of them, and you've never faced anyone as powerful as me. As soon as I get serious, this little match of ours will be over."
[She seems a bit unstable. Almost as if her physical immaturity was having an effect on her personality...Or maybe she just has a screw loose after living for more than a thousand years. Either way, I can use this to my advantage. I don't have the mana to get into a battle of attrition, so I need to kick this into high gear.]
Mike gave her a level look. "I've only known you for a few minutes, and I can already tell that you are a certain type of person."
The vampire narrowed her eyes in displeasure. "Oh?"
"In my homeland, we would call you a poser."
"Poser? Is that supposed to be an insult?"
He smirked. "Only if you think being called a jumped-up weakling with no real skill to back up your claims is an insult."
Esmerelda's face became emotionless as a wave of unseen pressure filled the area. So intense was her sudden presence, that it even caused the other two combatants to stagger, briefly bringing a halt to the dangerous game of cat and mouse they'd been engaging in.
A dark and ominous red aura surrounded the girl, and she raised one hand in his direction before growling. "I was planning on taking my time with you, but I think I'm going to kill you now."
As soon as she'd finished speaking, the aura surged forward and attempted to latch onto him. Feeling a deep sense of foreboding about the whole thing, he quickly leapt back while creating a mana shield. The tendril of dark energy passed through the wall of mana like it wasn't there, and continued chasing him, forcing him to continuously evade.
"That won't help you." The vampire announced while he was still moving around quickly. "Once my ability has been activated, you cannot escape it. So long as I retain my consciousness, it will continue to seek you out until it has reached you."
[Some kind of sure-kill technique? But that seems contrary to the nature of the System. For every method of attack, there is at least some means of defending yourself from it. Maybe this ability has some kind of activation requirement?]
Deciding that offense was the best defense, Mike dodged the tendril one last time before launching himself in Esmerelda's direction, sword clad in a sheet of flames. He trailed the tip of the blade along the ground and, once he got close, swept it up diagonally to both sever her outstretched arm and cleave into her torso.
At first, it looked like he'd succeeded in cutting her in half, and he felt a cautious optimism. However, it was quickly dashed when he saw a smile on the vampire's lips. A sudden chill swept through him as a dark red aura began crawling up his body. It took a moment to realize that her ability must have activated.
He leapt back to create some distance, and as he was doing so, he noticed that Esmerelda's left hand, which had been originally hanging at her side was raised, a similar dark aura surrounding it.
[Shit. I fell for it.]
With the same kind of blood-like tendrils as before, she reconnected the two halves of her body, and in less than a second was standing whole and undamaged. Glancing down at the shredded remains of her dress, she frowned for a moment, and then the bloodied rags began sewing themselves back together, albeit in a much rougher form than they were previously.
"I liked this dress, but I suppose it is a small price to pay to lure you into letting your guard down. Now that my ability has activated, any chance you had of surviving this fight has come to an end."
Mike tried using Appraise on the aura, just in case it had some effect, but unfortunately it wasn't recognized as a legitimate target. That being said, besides the visual aspect, there didn't appear to be any actual effects.
"So, is this supposed to be some kind of delayed death curse, or something?" He asked nonchalantly.
The vampire tilted her head slightly. "Hm, you don't seem to be worried yet. Very well, let me demonstrate."
She raised one hand and without any further explanation, stabbed herself in the stomach. Almost immediately afterwards, Mike felt an intense pain in his abdomen, like someone had impaled him with a red-hot poker. Looking down he saw a fist-sized hole had appeared just above his navel.
Caught by surprise, he staggered and nearly fell to one knee at the sudden agony.
"HAHAHA! How's that for a poser?!" Esmerelda mocked while pulling her hand free. "Do you see now how it is all hopeless?"
Spitting a bit of blood out, he took a ragged breath and replied. "So your ability is basically linking our injuries? And because you can heal so easily, that means you can inflict whatever kind of damage you want on your enemy without them having any chance to defend themselves. Is that it?"
"That's right, and because I have the power of vampiric regeneration on my side, I can recover from practically any injury. Can you say the same for yourself?"
[What the hell? Why do I feel like I'm going to be sued for copyright infringement?]
Mike straightened and scratched the back of his head with his free hand. "Well, to be honest. I can."
To prove his point, he lifted his shirt and showed her the site of his previous wound. Clean, freshly healed skin was the only thing left to see.
"Wha…How?" She started, before repeating the process with a stab to her heart.
This time Mike did go down to one knee for a few seconds, but quickly stood up once his healing had finished.
"Eh?"
A few more holes were made, to little effect.
[Looks like Aberth's gift was pretty effective. I'm healing roughly three times as quickly as before, and there is virtually no burden on my mana. So long as I am not forced to regenerate any body parts, I could conceivably keep this going indefinitely.]
"No way!" Esmerelda exclaimed as she continued to stab vital locations as she talked. "How in the hells are you doing this? My ability is in effect, but you aren't dying. There's no magic activation, no skill usage, no mana absorption. You aren't borrowing the lifeforce of nearby living beings, nor using a scapegoat substitute to avoid the injuries in the first place. And I can tell by the smell of your blood, you are just a human, so how?"
Gritting his teeth against the unpleasant wave of injuries, Mike did his best to appear unfazed by the assault. Based on what he knew about the magic systems of this world, he had to assume that her ability must be consuming mana in some capacity. It was unclear exactly how much, but he figured that it's ability to essentially overwrite reality must be very draining. As such, the longer he kept this going, the better.
However, he also didn't really have the luxury of waiting on her to gradually run out of power. Selene was holding off the other one for now, but there was no guarantee that she could continue to do so for long. Not to mention the fact that there was a very real possibility that they had allies that could come reinforce them at some point.
So, he decided he needed to egg her on further. Or at least that was what he was planning.
"Ahhh, this sucks!" The vampire suddenly exclaimed. "This is the best way to kill someone. It's so satisfying to see their faces once the realization of their own hopelessness sets in. Now I have to deal with this freak who doesn't even have the decency to be actually scared...Hmm. Now that I think about it, I bet you don't have a means of reattaching your head if you get decapitated, do you?"
[...Eh?]
Esmerelda evidently noticed his consternation before he had a chance to school his features, because she immediately gave a satisfied grin while placing one hand against her own neck.
"Shit." Mike grunted while trying to launch himself forward in an effort to stop her before she made her move. However, he could clearly tell that he wasn't going to make it.
For one brief moment, he thought for sure that he was done for, but then he felt the old familiar sensation of one of his skills leveling up. As it did so, the aura surrounding him wavered and then disappeared, leaving him standing awkwardly a few paces away from his enemy.
They stared at each other for a full second while both parties tried to figure out what just happened. Finally, Mike took a moment to investigate and learned the truth.
"Ah...my Curse Resistance leveled up."
I should know better than to make a timeline promise at this point. In my defense, the delay was partially caused by an ill-timed power outage.