Let me see if I've got this right: The Master implants his eye into his Keyblade (ouch) which he then passes on to Luxu. Luxu then goes off to follow The Master's instruction because the eye transmits everything it sees back to The Master no matter how far into the future. Then Master then uses his future vision to pen the Books Of Prophecy to be handed out to his five other apprentices. Does this go against the rules of time travel that were established in Dream Drop Distance?

Think about the eye as a recorder of events. The eye records everything Luxu and his disciples see and the Master can see everything the eye will record/has recorded. So when the master gained this ability, he already could see every future event the eye recorded and he wrote those events in the book of prophecies. The moment he put the eye in the keyblade (I think) he could not longer see future events. Since aparently, both the eye and the ability to record events can't die as a normal human being does, it's not time travel.

Think about the eye as a recorder of events. The eye records everything Luxu and his disciples see and the Master can see everything the eye will record/has recorded. So when the master gained this ability, he already could see every future event the eye recorded and he wrote those events in the book of prophecies. The moment he put the eye in the keyblade (I think) he could not longer see future events. Since aparently, both the eye and the ability to record events can't die as a normal human being does, it's not time travel.

That just raises more questions. Like where did he get that power in the first place and why is he recording what he sees and passing the Books out if it's impossible to change the future? If he's the original Keyblade Master, where did he get his powers if the only way to get them is from another Master? Just everything about this guy is... well nothing because we don't know anything for there to be an everything.

Well hey, what can I say, I'm a man of mystery! I bet you're dying to know the secret behind my eye...huh!? Huh!? Don't you wanna know!?

 

But well, even I can't answer that question.  Yeah, I'm the original Keyblade Master, but even I don't know how I got my power...not much explanation was given to me for everyone else to see, and so I'll leave it at that! As for my eye, well, since it's simply a means of recording events of the future so I can write them down in my book, it technically doesn't count as time travel! In fact, maybe some alchemy was involved in this whole mess, since there's lots of chemical, experimental flasks in my chamber, ya know? So I could have easily added some alchemic touches to my eye placed on old No Name, and it could've transformed into a recording device because of said alchemic touch! Hence why my eye can see into the future without me having to time travel into the future!

 

I know, I'm confusing, aren't I?

Well however he got his powers to see the future, I think one possibility about the reason he needs to have Luxu take his Keyblade and eye around everywhere is because it's a form of "paying" for his foresight. Like let's say his eye seeing everything is what allowed him to see the events of the future before before he wrote the books. Now in order to make sure that stays that way, he has to make sure he gives it to Luxu so that he can carry on through time recording everything with the eye so that the Master will have always had that knowledge of the future in the first place. It's like setting up a tab I guess. He already got the knowledge of the future, now he just needs to make sure he can "pay" for it by having the eye witness everything so that he would have known it already. It's not technically time travel, as no one is traveling through time in any way other than the natural method of progressing forward second by second. Master stays where he is...wherever he is...and Luxu flies away from the destruction of the War to live on to pass the Keyblade to whoever his apprentice becomes, and then that person to their apprentice, and so on, until it eventually comes into the possession of Xehanort. Who knows what happened to Luxu after he passed it on, maybe he passed on himself, naturally speaking of course. Or maybe he just disappeared to wherever his Master went to. In any case, we won't know for sure for a while.