Rhine Arcedia

Backstory
A man was just living his life when he was killed by another person. But this wasn't the end of the man's story but just the beginning.

The man ended up reincarnating as a slime in a different world and he went on adventures making a lot of friends. Unfortunately after a few years the slime ended up going against an immeasurably strong opponent and while the slime ended up coming out on top he lost a portion of his soul as the price.

The portion that was paid didn't end up disappearing but instead ended up being blown to a different dimension where he was reincarnated into a human baby named Rhine Arcedia.

Rhine grew up living a slightly exciting but fairly normal life until he reached the age of 10 and his memories started to recover and he remembered who he was.

Thus with his memory Rhine started to train in magic to try and get back to the other dimension but unfortunately while he had a monsterous capacity for magic power Rhine wasn't the part of the soul with the talent for controlling magic power so he couldn't control his spells at all, and as a a result when he set up the ritual to test teleporting he ended up being teleported to an ancient dragons den, Rhine used his powers and could just barely stay alive against the traps the dragon set up but fortunately for Rhine before he lost his life the traps were disarmed by someone.

That person looked at Rhine and was amazed at how Rhine used his magic power to brute force his way through the dragon's trap and he got curious about him so he forced the kid to tell him his story, his response after hearing the story was:  "hahahaha what a funny kid. You have so much talent and potential, how about becoming my disciple? This isn't a suggestion"

After leaving the den that man told Rhine: " that was an interesting story you told me how about making it into a book?" And while Rhine was busy contemplating his life his Master ended up turning that story into a book and selling it for money. When Rhine went to confront his master about it he was beaten up and then told it was a lesson as to how the real world works.

After becoming that man's disciple Rhine ended up growing rapidly, just kidding he didn't get any stronger. Rhine truly is useless when it comes to most forms of magic, aside from space and time and wish magic which he has a slight ability in.

Fortunately for Rhine while he couldn't increase his abilities he could increase his knowledge as his master was one of the smartest and strongest people in the world and combined with the knowledge he had from his past life Rhine ended up being a walking library of magic. Unfortunately for Rhine he wasn't that smart, just very knowledgeable.

Rhine ended up receiving a staff as a gift from his Master after seeing how useless he was, the stuff was supposed to be an ancient powerful relic but as always Rhine was useless and couldn't use the staff abilities.

After a few years passed and Rhine became 17 his master eventually got tired of teaching his useless apprentice so he opened a portal to a random dimension, threw Rhine into it and told him to find a way back.

And that's how Rhine started his journey in a different world without anything but his clothes, staff and knowledge.

Powers
Rhine is useless when it comes to most magic in a sense that he can't control his spells so that while trying to attack the enemies he might buff them instead but he can use some time and space and wish magic, still not very good at it but at least it's usable.

Probably because of the influence from his past life, whenever Rhine uses magic black flames will appear. Like when Rhine teleports black flames will appear to swallow him from his feet and then if he is lucky somewhere near his target black flames will rise up from the ground before disappearing and Rhine will appear there.

Because the effcts of the spells are random, a spell can also be enhanced, for example turning a small fireball into a meteor.