Awakened Earth!!

"I'm currently sitting on a chair in the audience. There will be several Battle Royale rounds in this Colosseum alone. As the winner of the previous round, I have to wait for this round before I'll be entered into the next round of Battle Royale. If you lose, you get eliminated. However, as I look at the people, I realize not a single one of them is a mage. Naturally, they all favor fighting with melee combat skills, meaning it will take forever. They all seem around my age range. The qualifying rounds seem to split us up into age groups. I fell asleep, and when I woke up, it was almost over. The next round of qualifiers had begun. Someone thought I suck at close combat because I am a mage, so I just casually blocked their powerful strikes with a turtle shell or dodged, utilizing magic shield or other defensive magic. When I done toying around with them, I just annihilated everyone in the entire Arena. This continued every time I went out to fight. I decided to just one-sidedly annihilate the competition it wasn't even close."

"I continue my overwhelming victories one after another. After all, since I'm placed with people in my same age group, it would be difficult for anyone to be stronger than me, my age group being anyone under a century. I explain that most people simply accumulate power over time, and with a long lifespan, there's really no need to go through the risk of training yourself to the brink of death. Most people don't train themselves to the breaking point, of course, with the S rank growth definitely helping. However, after so many annoying and tedious rounds, I'm starting to get sick of this. They should have more experience than me in some cases, but realistically, they still aren't even on my level. I'm like an unstoppable force making my way through the tournament."

"Another round, I make my way into the arena. Screw this, it's been three whole days; I just want to get some fucking sleep in a bed. I utter the words 'unique magic: Rainbow Flame Transformation.' My eyes turn rainbow, my hair turns rainbow-colored, and my wings turn rainbow-colored. My clothes are incinerated and replaced with a dress made of solidified rainbow flames. Despite the appearance of these rainbow flames, they are composite all the magical elements. They simply take the form of fire, and they are capable of quite literally burning anything: space, time, reality itself. However, the problem is, it's one of the magics that can harm its user. Spirit magic summons a spirit to manipulate and create natural phenomena, so it makes sense why it can harm its user, but normally one have complete control over there magic so harming oneself should be impossible. Guess there are always exceptions to the rules."

"How do you stop a fire that can literally burn anything from burning oneself? That's how I perfected this magic and finally got it to the unique grade. The answer is simple: you simply have to become the fire. My ridiculous magic powers make the entire Coliseum shake. No one seems intimidated. I simply said in a voice that sounds like it comes from the depths of the Abyss, so immediately surrender if you don't want to die."

"No one took me seriously? One guy even charged at me. I didn't even block his sword attack. Similar to a Logia Devil Fruit user, he attacked and passed through me harmlessly, as if my body was made of rainbow fire. That's right, in this form, physical attacks cannot harm me. Even if you were to coat your sword in mana, it still would be unable to harm me. You would need to activate some sort of enchantment on your weapon. Like, for example, if you had a flaming sword. Since it's a magic attack, my intangibility will not work."

"Don't think the emergency barrier can save you," I laughed maniacally, about to actually attack. However, the referee immediately said, "Stop! I declare Crystal the winner of the entire preliminary round of this Coliseum." Before anyone could complain, the referee knocked every single other competitor out. I couldn't even see him move; he's ridiculously strong.

I undid my transformation, quickly removing a new set of clothes from my spatial ring and using the spatial magic of the ring to equip them to my body. It takes a bit of practice, but it's a convenient trick. You can even use it to quickly swap clothes.

The referee looked at me and said, "To think someone so young has developed their own grade of unique magic. Normally, even if one was using unique magic, it should be impossible to defeat someone like myself given the difference in power levels." But that fire can literally burn anything, meaning any defensive magic I could use is also included on that list. The only way to defend against it is to actually use magic that is of equal or greater power to cancel it out. Quite impressive."