Difficult Spell idea (need help)

I'd like to make a spell that works like chain lightning, except, instead of doing damage, it casts slow on every target it jomps to. I played with healign wave, chain lightning, even the wand of neutralization, and couldn't make it work. i need to do more than the war3 editor allows me to do. where do i begin my quest to get this 'chain slow' spell to work?

any help is appreciated.
:)

i think you could use triggers so when the unit is hit with chain lighting or whatever the ability have like a fake invisble wisp created (the wisp will have slow) and then make it cast slow on the unit, then remove the wisp.

only thing I can think of is if theres a unit hit my spell event or seomthing.... You could use a trigger to slow movement + attack speed + add the SE then remove them when needed.