[quote=@Sanity43217]Could you use Aura shortcut magic? Like if Aura can replicate other forms of energy like fire, could it replicate Mana and be used to substitute parts of magic equations?[/quote]

This is a question I had not even considered! Excellent work! I'm going to say "Yes, BUT," with the but being that using Aura to substitute for Mana is extremely dangerous because you're basically burning HP to replace MP. If you were to do it for a high level spell, or a spell that requires a "constant" Mana drain over time, you would very likely kill yourself unless you had trained to heavily expand your Aura reserves.

I will also say that, in the reverse situation, if you came up with a Magic spell that mimicked one of the Aura types, it would not usually work in pitched battle the way Aura does. Aura becomes an extension of the warrior using it, whereas casting a spell would require you to stop swinging your weapon so that you can focus. The more variables a situation has---and a one-on-one fight has a lot of them---the more difficult it is to adjust the variables of your Magic Formula. Now, if you had a spell that could do the same thing as Aura Augmentation, you could potentially cast it BEFORE going into battle to buff your weapon or that of an ally, but other than that the uses of mimicking Aura with Mana are less intuitive.

[quote=@Crowvette]So if there was a practiced mage who was sent back, due to the knowledge-based nature of magic as described, they would basically still have their failed timeline magic ability completely intact? As compared to an Aura which would likely need at least some training since it's more of a muscle than pure technique?

I'm not necessarily calling it out as an imbalance and maybe you answered that question already but I just wanna be sure. I think having a magic system would be fine, though I might have a slight preference to just a wider array of Aura options over Aura and Magic coexisting.[/quote]
You're correct in that the knowledge of magic would come back with the Regressor. You are also correct that, even if you managed to eventually Awaken in your First Life, your past-body won't be quite as developed yet and thus your Aura would be temporarily locked again.

However, remember that Aura depends on having a certain level of physical/mental/spiritual balance AND a certain level of skill mastery. Your past body might not yet be developed enough, but your mind and spirit have remained the same and you still remember the skills you gained. Maybe your physical strength is lacking---but you remember techniques that the past you hadn't yet learned, you have tactics and strategies and familiarity that you didn't before. Not only will you regain your Aura much faster in the Second Life, but you'll also be able to pull off a lot more impressive stunts than you could originally.

Let's say a character had their first "sparring test" at the Collegem, and in the first timeline they just ran in, swinging wildly, and immediately got parried and riposted before getting bashed over the head. But, this second time around, you actually know how to take your stance; you feint, bait your opponent's techniques out and counter them, interrupt his footwork, etc. To the [url=https://josefcd904.wordpress.com/wp-content/uploads/2018/04/hinamatsuri-ep-2-pic-14.jpg?w=1400]instructor[/url] who's been watching you, it suddenly appears as if this talentless nobody has suddenly become an experienced fighter! "NANI!? M-MASAKA!?!"