Morgana's Ult and Kalista's Passive Art

Hello, I was wondering if anyone could shed some light as to how these were created and how they work ingame? I've been trying to do something similar to create a "Dark Chain" of sorts for a Morningstar wielding character but am stumped on how to solve a few problems. I can get the foundation (the darkness) working but what's stumped me is trying to create a flowing pattern that animates within that darkness. I can easily create stuff ontop of it and whatnot but making it as I've designed it isn't something I've figured out yet.

Darkness foundation is created by simply creating a bunch of particles in a line from the morningstar to the character and then drawing some wiggling particles on top of them to add in some form of movement.

The red bit I want to look something similar to this: http://i.gyazo.com/6e6ddfec3905d6d0dcb34d6f5f9ebad6.png

And here's where it is: http://i.gyazo.com/b051ba352b9ad5151888f20a01e954b0.mp4

Feel free to ignore the dark soldier bit. He's a stand-in (and someone else's art!) while I develop all of the art assets.

My initial idea was simple: Get the offset from the soldier to morningstar (ie where has the morningstar moved this frame from last frame?) and simply adjust all of the particles from there.

But this introduces the problem of radius differences. And there are other problems as well. Anyway; just wanted to ask and see if I could get an answer :)