@EATARI
Thank you! The answer to your question is kind of long(?) - I don't know how specific or detailed you would like the information but I will try to explain without being overly long or too vague. Also I'm still on the ropes for learning vfx stuffs myself :s.
First off, the VFX would not have been possible without the base iteration of Ryze. There is a very sturdy framework for you to build your ideas ontop of within it. Like the way certain projectiles are shaped, the way some of them explode - the language of the VFX is very clearly explained in the base skin. All I did was adopt the formula provided by Riot's original skins and redesign some of the colors and shapes to make something new. Like the original rune trail texture provided by Riot was a godsend, an absolute necessity for this design to work as well.
In the end, a lot of it is trial and error. You just keep doing stuff until they start looking nice. Like the shield speed tails you mentioned, I was kind of on the edge of that and another version I had made. You just keep iterating and hopefully, it turns out okay :D - but sometimes it's a little ambiguous and/or not as good as as you hoped it to be. As I'm making the effects, I'm also replaying SkinSpotlight's video a million times lolol.
@Manxxom
Please revert ryze to pre 9.14 xD.