Channeling Beam Spell

[nafre]

Hi can someone help me make a spell like phoenix's Sun ray spell from dota. It can be either jass or gui. And i need it to be mui and channeling and can be turned on and off. Here's the spell preview picture.
P.S. I dont care what lightning you use.

Credits and +rep would be given.
(If anyone finds any problem or typos in this post please do tell.)