Heartbeast has allowed me to use the sprites from his GameMaker turn-based RPG course but has asked that anyone else using them only do so for educational purposes and not for commercial projects.
This project is the result of converting Heartbeast's Make a Turn-Based RPG in GameMaker Studio 1.4 to the Godot Engine, with some documenting, it can be used as starting point or guide on how to make your own RPG battle system.