Custom Spell Question

[PublishedShadow]

I'm planning on creating a Hero spell that has (5 levels).
Essentially, I want to combine Mirror Image and Wind Walk. So here's my question:

The Spell Overview:
My Hero casts the ability, creating a Phantom (or mirror image) of herself. Upon creating the Phantom, she becomes invisible for X seconds, gaining increased movement speed of 50%. If she breaks invisibility by attacking she will deal X damage.
-The Phantom will deal X% damage and receive X% damage with each level.
-Invisibility duration and Damage dealt upon breaking invisibility increases with each level.

I plan on doing this by basing the hero's spell off of mirror image. Once the ability is cast, a dummy unit casts my invisibility and a speed boost on the hero.
I could then have a separate trigger for her that checks for my invisibility buff and then if she attacks deal X Damage.
The only negative that I can currently think of is I will need 5 invisibility abilities with 5 different buffs for this to work properly.

So, does the above seem the easiest/most efficient way to do this ability?
NOTE* not aiming for MUI and it will be done in GUI with some custom script.

 

[RobertMKD]

How can a dummy unit make you invisible?
What you probably want to do is create an illusion of the hero by trigger when she activates wind walk. Just like DotA's spell that creates an illsion at the position of the caster and makes him invi, confusing the enemies.

 

[PublishedShadow]

How can a dummy unit make you invisible?

Using the invisibility spell (human - priestess)

Actually yeah, thanks. I completely forgot about the Item - Illusions ability. That could work too. Probably Less Triggers that way.

 

[Daffa]

The base is Wind Walk, then use some minor trigger to utilize the illusion.