I cannot find any information on them. Should I buy them? And what are the mage amulets for as well?

https://subeta.net/forums.php/read/839821/Stat-Booster-List-v20 See under 'A Mage and his Tomes' :)

I would say they are reliable boosters, and really good bang for your buck.

Thank you very much . I bookmarked the page to keep track of the information.