In this fanfiction, Naruto could have planned it all out in advance. He might have known about the incoming threat and decided to fake his death as a strategic move. He could have used his knowledge of the area in Wave to his advantage. Maybe he found a hidden spot where he could disappear and make it seem like he was killed. He could also have used his skills in stealth and misdirection to make the whole thing look convincing. For instance, he could have left some of his blood (from a minor injury he had before) at the scene to make it more believable that he had died.
Well, he might use some substitution jutsu. He could replace himself with a log or something similar at the crucial moment, making it seem like he's been killed.
Perhaps he gets help from someone in the Wave village. They could create a diversion and make it look like Naruto is dead. For example, they might use some special effects or illusions to deceive the enemies. Also, Naruto could have used his shadow clones in a clever way. He could make a clone appear to be fatally injured while he hides himself. This way, his enemies would think he's dead.
One possibility is that Harry uses some advanced and little - known magic. He could have found a spell in an ancient book in the Room of Requirement. This spell might allow him to project an image of his death while he actually hides himself in a magically protected space. He may also have made arrangements with the Order of the Phoenix to spread the news of his death convincingly.
One consequence could be that his friends are devastated at first. They might go through a period of grief and self - blame for not being able to protect him.
Well, Naruto could have made a deal with some powerful being or used some sort of forbidden technique. Maybe he found a way to transfer his life signs to another object or being, making it seem like he was dead. He's always been resourceful and full of surprises, so faking his own death in a really elaborate and unexpected way is not out of the question.
Maybe he used some rare magical artifacts. In the wizarding world, there are many mysterious items. He could have found an artifact that allows him to project an image of his death while he actually hides in a magically protected place. It's also possible that he faked his death by making a deal with some magical creatures that are good at deception, like the house - elves. They could have used their magic to make everyone believe he was dead.
One possible reason could be to protect his family. After the war, Naruto might have made many enemies. By faking his death, he could draw the attention of these enemies away from his family, especially his wife and children. His enemies would think he's no longer a threat and stop targeting his loved ones.
His friends might feel betrayed. They would be mourning his death while he was actually alive. This could lead to a lot of anger and mistrust when they find out the truth.
Well, it would probably shock everyone. Sasuke might feel betrayed as Naruto is his closest friend. For Boruto, it could be a huge turning point. He might start to question a lot of things and feel the need to step up more. His relationship with his friends and family could also change as he tries to deal with the fact that his father is 'dead'.
One possible plot development could be that Naruto fakes his death to outwit a powerful enemy. He might go into hiding, secretly gathering information and allies to strike back at the right moment.
Another possibility is that the main antagonist is a group. It could be a secret organization that Naruto discovers is plotting something big. Since they are so powerful and well - connected, Naruto fakes his death to infiltrate them and expose their plans from the inside.
The Death Eaters might think they've won at first. There could be chaos and fear among the good wizards. But it could also lead to a secret resistance growing stronger.