[LE] Scripted spells

[IanGray]

I can't say that I'm a total beginner with modding and I've accomplished a few things prior to this. It's been quite a while and I guess my knowledge have dropped off and I'm feeling a bit confused about some aspects of the Papyrus scripting and that with spells.

There's a spell already available that does pretty much what I want, but I'd like to learn what it does so that I can in the end create my own variant of it to have on my own playthrough.

The spell/magic I'm referring to is the Bat Travel by @DidymusEi

Looking through the spells and where they lead and what scripts they call, I'm now entirely lost and I'd like some help figuring this out.

I realize I could just go into the mod and alter these things on my own and have it work pretty much like I want it to, but as I said, I'd like to intergrate it into my private mod. Instead of me just changing the effects.
The current intent is to try and make the bat travel spells into some sort of nether type thing, you don't become a cloud of bats, you become a dark cloud or just something different.

So, in short, I guess what I need help with is some explanations on the scripts in the Bat Travel mod so that I can create one for myself.