Stone Form - Being casted on other units?

Stone Form - Being casted on other units?

Since just changing the target field of Stone Form won't work I will have to base an ability off of hex/polymorph and use triggers.

I also want them to become grey (I can do this via tinting but can it be done via triggers?)

I'm real unsure on what I need to do with triggers :\

Could anyone give me a little direction here?

U will have 2 make a custom stone form. (So all those units wont get animations etc)

just make a custom target based ability. Preferably without buffs (Finger of Death)

(This trigger only works if the ability strikes the unit with no time in between (Like finger of death))
Events:
Unit begins casting an ability
Conditions:
Ability = Stone Form
Actions:
Pause Target unit of ability being cast
animation - vertex colour to 50%, 50%, 50%

I think there is no better way to do it