Upgrading the fox’s stats in Tunic is essential for completing challenging dungeons and defeating bosses like the Librarian or the Seige Engine. There are six different items that players can use to upgrade various stats, including health and attack. Upgrading the fox can be done early on in Tunic. However, the items and what they’re used for won’t be revealed until players collect some of the pages for the instruction booklet.
https://screenrant.com/tunic-upgrade-items-how-to-use-guide/