In Naruto fanfiction, cheat codes can drastically change the use of jutsu. They might allow a character to instantly master a jutsu that usually takes years of training. For example, a cheat code could give Naruto the ability to use the Rasengan without any training from Jiraiya. It's a fun concept that adds an interesting twist to the Naruto universe.
He might also draw inspiration from his friends' jutsus. Sasuke has some powerful fire - based jutsus. Naruto could think about how to counter or incorporate those elements. He could try to merge his own wind - style with Sasuke's fire to create a new type of jutsu that has both the intensity of fire and the cutting power of wind.
He could practice in secret locations where no one can see him. For example, in an abandoned cave or a hidden part of the forest. That way, no one will know about the new jutsu he's developing.
Well, in certain fanfic scenarios, Naruto could learn paper jutsu as a result of some experimental training. For example, he might be trying to combine different elements of his existing jutsu and accidentally discovers a way to manipulate paper. It could be that his chakra takes on a new form during a particularly intense training session and he realizes he can control paper with it.
Naruto was able to dispel the fireball with a boeken because he had trained hard and had a deep understanding of his powers. He made a split-second decision and executed the move perfectly, surprising everyone.
I think Naruto might have had a sudden burst of inspiration or strategic insight when using the boeken to dispel the fireball. Maybe he combined it with a previously unknown jutsu or found a flaw in the fireball's composition and exploited it with the boeken.
To create a jutsu in Naruto Jutsu Maker Fanfic, look at the existing jutsus for inspiration. Notice how they are named, what they do, and how they are used in battles. You could base your new jutsu on a character's personality or backstory. If your character has a connection to water, like growing up near a big lake, maybe the jutsu involves creating huge water serpents. Another aspect is the chakra consumption. Decide how much chakra your jutsu will use. If it's a very powerful jutsu, it should probably consume a lot of chakra, but you can also create some low - chakra - cost jutsus for quick and repeated use.
In fanfiction, the reanimation jutsu might have extended or modified limitations. For instance, in the original, there were clear rules about the caster's control over the reanimated. But in fanfiction, a writer could create a scenario where the reanimated can break free of that control more easily. Also, the source of the sacrifice for the jutsu could be different. In the series, it was usually human sacrifices, but fanfiction might explore using other forms of energy or substances.
Well, Naruto could start by observing his surroundings. For example, he might notice the way water flows in a stream and use that inspiration to create a water - based jutsu. He has a lot of chakra, so he could also combine his chakra nature with his unique experiences. Like when he was training with Jiraiya, he learned about the toad - related techniques. He could take elements from those and add his own spin. Maybe mix the rasengan concept with some new chakra manipulation based on his time with the toads.