Spells are the basis of the server.
Almost all content is based on these spells, so it is important that there are a lot of them, and that they are implemented correctly.
The Invert Projectile, which flips the target upside-down.
To create spells, you don’t actually need Java, or a specific editor for Java files - all you really need is some sort of editor that allows you to create a file.
This is because when creating a spell, you don’t actually have access to the plugin to run it - only server admins have access to that, so you only really need to be able to edit a file or two.
That being said, it would likely be much easier if you had a decent editor - any of the below options are good choices.
Note that apart from IntelliJ (which requires an extension), these editors do not have automatic autocomplete for either custom, spigot or NMS methods.
Another thing that helps a lot is previous programming knowledge - whether that is Java or another language.
If you don’t know how to program and you’re interested in learning Java for the future, this tutorial could be a useful thing to look at before starting, but if you only want to create spells, a number of Java methods and programming notes will be included further along in this doc.