THIS COMMENT IS FOR GIVE THE DESCRIPTION OF THE STORY AND IS MADE BASED ON THE SYNOPSIS FOUND IN THE PAGE JAPANESE PAGE WHERE THE WEB NOVEL IS RELEASED (https://ncode.syosetu.com/n6309ex/) AND THE FIRST CHAPTER OF THE MANGA, THE TRANSLATION IS MADE USING GT
MAgnus is a skilled wizard able to use various attribute and is part of a party.
Unfortunately for him the leader of the party make him use the wrong spells against monsters and since they don work, the party think that hes useless and treat him badly.
One night, after another unjust mockery, he go away and is reached by a merchant that sell him a book... from it he learn various things about monsters and the next day try this new knowledge for discover that is all true...
Now its his turn for shine under the eyes of a party that think of him as someone useless