Haha, thanks so much! We really wanted to add Reletrix and even had a special mechanic in mind for his boss fight. However, in the end, we decided to use the last hours of the jam for polish, bug fixes, and making usability improvements (e.g. card tooltips)… Otherwise we were afraid people would never care to make it past the scarecrow fight let alone wish to see the endgame.
I can’t make any promises yet but we will definitely remember your comment as we decide whether to add more content!