Aura, is a type of power similar to magic. If magic allows the user to manifest something from nothing but mana, then an Aura will allow the user to temporarily enhance their body instantly by using their stamina as a fuel.
A mage is capable of casting spells, the amount of spells they can cast depends on how much mana they have in their mana core that is located in their heart, as their mana keeps on depleting, a mage will begin to slowly feel more exhausted, until they can't no longer move their body and unable to stand up, this condition is called a mana exhaustion, and it is the time when a mage is most vulnerable, since their mana core is basically their heart, if all of the mana inside of it is gone, then their heart would come to a complete stop, resulting in death after just 10 seconds.
On the other hand, Aura user were different but also similar to how a mage works, but instead of having a mana core, they instead developed a core that's meant to store energies, it's called an energy core. This abundant source of energies is what makes an Aura user capable of using aura, they basically have a backup storage for their stamina and that's what makes it advantageous in long battles.
This is also the reason why it is almost impossible for a mage to awaken their aura, because with 2 separate cores, their body wouldn't be able to handle it and crumble completely.
Different from magic that can only used by people who are born with a mana core, anyone can awaken their aura without innate talent, there's multiple cases of someone who trained their swordmanship for years managed to obtain an energy core out of nowhere, some people believed it is the fruit of their hardwork, while others believed they're just lucky. Whether or not those statements are true, there's no denying that it is a possibility.
A mage can learn from theories and magic circle formulas, the size and the complexity of their magic circles is what determines their magic spells, most mages only uses the simplest magic like fireball, water cannon, or wind cutter. These spells requires simple magic circle, and mages would just adjust their power based on how much mana they put into the spells, it's a common choice for continuous attack.
As for the issue with lack of mana, there are multiple ways to increase your mana capacity, one of them is to meditate and gather mana from the outside, however this method is perceived as inefficient since it usually took more than a year just to increase one's mana by 5% with daily meditation.
Meanwhile, with aura, it's different. While there is still a variety of different enhancement, all of it is just elemental, it means that an aura can comes in many different elements like fire, water, wind, earth, light, and dark. How to use the aura is depends on the user entirely though, some people think it's better to put their aura in their weapon so that their sword will be engulfed in fire of their elements, enhancing its power and adding many attributes to it, while some people think using aura around your body is the best way to use it, with their body enhanced with aura, their strength and senses would be multiplied.
Either way, the two method can still be a game changer that will turn the tides of battles.
"That's why.. I trained everyday.." Said Carsel, he saw his father walked out of his sight, his hand still gripping the sword hilt tightly. "I pushed myself– So that i can awaken my aura.. Why can't i awaken? I've trained for years.. Yet.. There's not a single sign of result, my skills grow, but without aura, im just a nobody.."
Saddened with his pathetic life, Carsel looked down and saw his leg, he remembered using those legs to dash and stab the air a hundred times, he believed in those stories about people without talent awakening their aura from just hardwork alone, but to him, at this very moment, he might no longer believe in those stories.
"Young Master!" A woman voice can be heard from behind, shouting towards the dejected Carsel. "I brought some lunch for you!"
As soon as Carsel heard her voice, a small grin appear on his lips, it was a light and relieved smile. As he turn around to see the face of the woman who just called her, Carsel then took a step closer, as he said..
"Alright, wait me there!" With a joyful tone.
***
CRASH!
Like the sound of a glass shattering, Carsel was suddenly thrown into the dark void again, he's now faced with death once more, but unlike before, he found a reason, he founf a desire that will overcome even death itself.
'DON'T CLOSE MY CURTAIN YET YOU ASSHOLES!! IT IS NOT OVER!! I– I– I WILL ARISE AGAIN, FOR MYSELF!! FOR HER!! UNTIL I MEET HER AGAIN—
Countless faces of a woman with glasses in maid dress flashed through Carsel's mind, it was quick like a machine gun, however, that face was everything Carsel ever wished for, her black hair that has a gradient of white at the bottom, and her green eyes that shines like an emerald, Carsel rose from his death and was greeted by a glowing scythe, the scythe design was different from the one that appeared on Calea's dark void, and just like her experience, the scythe then slowly descended from the sky to meet with Carsel as he reaches to it with his hand.
'This scythe.. I see, so this is what he meant— EVERYTHING I'VE BEEN TAUGHT, I'LL USE IT TO RISE AND SURVIVE! FOR THAT DAY WHERE I CRUSH ALL OF YOU!!'
Swoosh!
Carsel was blinded by a bright light, it was as if he was now in a white void.
However, at the outside of his subconsciousness and into the real world, only a fraction of a second had passed in there, and to the two cloaked men, they only just saw Carsel falling to the ground, seeing his unconscious body sparked their excitement, they were about to grab Carsel by his collar when out of nowhere, a small flame began to lit on of his closed eyes.
"Huh? What is..." Said one of the cloaked man, he noticed the burning fire despite the rain.
Just then, Carsel woke up from his slumber and grabbed two of cloaked man's wrist, the fire extinguished, and his eyes opened, revealing a turquoise eyes. He uses the cloaked men's wrist to support himself and pushed his body up.
"W- WHAT!? H- Hey..." Said the cloaked man, he was shocked to see Carsel standing up like nothing happened. "This kid–
"Let's continue, sorry for that, assholes." Said Carsel mockingly, wiping the dirt and water away from his face.