How could I create a buff to remove collision size?

[Dovekie]

What I am trying to do is make it so that when a certain hero is casting a Bladestorm type ability, he has no collision size. Like a wind walked hero or like someone using phase boots in dota.

I thought of a couple ways--

The first was to apply the buff "windwalk" to the ability and then to go make it so windwalk doesn't make you invisible, but the options for editing buffs are extremely limited, and that wasn't an option.

The second was to create a trigger like this
Event:
-Unit - Unit begins casting ability
Condition:
- [Ability being cast] equal to Bladestorm
Action:
-Unit- Turn collision for Unit Off.

This seems like it would work, but it won't let me select the hero. When I try to, it makes me click on a unit on the map, but the unit hasn't been created yet, so it isn't on the map.


I'm sure it is very simple. I am just pretty noobish at the editor and have been trying at it for a while now.

 

[Imp Midna]

Next to the button you can use to choose a unit, click on the drop-down list and choose "Triggering Unit". It will always refer to the caster of the ability and, therefor, turn off the collision for the caster.
The Trickier Part will be to actually turn it on again once Bladestorm ends. The Easiest way is to use "Wait (x) seconds", where x is the duration of Bladestorm, and then use "Unit - Turn on collision for Triggering Unit On" respectively. Note that Wait is, however, a little inaccurate (~0.25 seconds usually), so the collision might be a little shorter, or (in most cases) a little longer than expected.
Doing it more accurately would require advanced knowledge of the trigger editor and timers.
Also, consider using "Unit begins to start the effect of an ability" as an event instead. At the event you are using, the spell may still be interrupted after the collision was turned off, granting a free no-collision-buff.

 

[KaerfNomekop]

You could also change the Fade Time for Wind Walk (or another invisibility spell) to a higher value than the duration of Bladestorm, so that the unit technically has invisibility but doesn't actually disappear.

 

[Juggernaut]

You could also change the Fade Time for Wind Walk (or another invisibility spell) to a higher value than the duration of Bladestorm, so that the unit technically has invisibility but doesn't actually disappear.

Doing this disables critical strikes afaik.

My idea is to use a timer. Since you know how long your spell will last then start timer when ability is cast with duration (total duration of spell). Then check when the timer ends and add collision.
Oh, I think Imp suggested the same thing before me..

 

[Solu9]

If you need the spell to be MUI and go with the timer idea, I suggest you take a look at this thread http://www.thehelper.net/threads/how-to-detect-which-timer-array-nr-expires.159419/ where I ask kinda the same question.

Because with more than one unit being able to use the ability. you will have to keep track of several timers.