As you want a visual try a visual only solution. Use a Query Region actor like the colossus treee killer.
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Considered easy altering of the unit textures?
http://static.sc2mapster.com/content/attachments/15/252/Screenshot2011-04-17_09_16_21.jpg
For my public assets look here!
http://www.sc2mapster.com/forums/resources/data-assets/46733-the-assets-of-evil/#1
darthuser3220 Regular ShmoeNeed some help with this one, tried using both a search buff behaviour and the main buff behaviour itself, in combination with the On Creep, Target On Creep Validators but I still can't manage.
If someone would be as kind as to show me an example in written or saved map file format I will very much appreciate it.