Nether Scrolls - pulling more stuff from DnD

hello chaps

its been a long time since i did a post about flying cities, inspired by the nation of Netheril from the Dungeons and Dragons setting the Forgotten Realms. Now i am back with more Netherese inspiration. The Nether Scrolls.

For those not familiar, the Nether scrolls were scrolls (duh) that contained pretty much all the secrets of magic known to a powerful, ancient and long dead race. Reading one immediately improved the readers magic (giving them another level in that games mechanics).

For my own homebrew campaign and setting i am thinking of introducing something similar, some thing very powerful and hence an excellent hook for magi to quest for and for enemies to try and take off them.

But i am stumped on how to implement it in game. i already have the plot all worked out, but not the effects of studying the scrolls.

The canonical scrolls gave insight into various subjects depending on what scroll was found. Since my players will find only one, i'd like some way for them to have a different experience depending on what they want to study. I did think about maybe making it an excellent quality tractatus on an art of their choice or in magic theory, but that doesn't sound terribly mythic and super whizzy.

Any ideas?