Click on the plus (+) icon in the Spell Browser Section and select your Save file.
Drag and Drop spells from the Spell Browser into your Spellbooks and hit Save!
Your Save file is here:
C:\Users\YourComputerName\AppData\Local\RSDragonwilds\Saved\SaveCharacters\
Disclaimer:
Data is compiled from the latest game files automatically.
I don't check if the file is a developers only spell or a test asset.
I compile it all and give you access to everything.
This means you should always back up your save.
It is possible to inject something that isn't allowed and it crashes.
According to the game files, this is every spell in the game, including dev/test spells.