League of Legends attack marker

Hello, I need some help.
I’m want to achieve a attack marker like the League of Legends has.
It’s very strange to me, I was thinking that Decals could make it, but the markers seems to ignore the meshes below it, not mixing to the texture.
Then I thought it would be an UI element, but it seems to come from below the character.
You can see, that it starts from the feet of the character and everything else forward, even if it is taller than the character get overlapped by it.
The question is, how I can get that result. I dont need scripts or blueprints, just want to know how could I do that. It seems alien technology to me. :wink:
This I got from a Decal:
But, I need this:
League of Legends 2014-06-06 02-52-31-262 (Small).png
League of Legends 2014-06-06 02-53-35-230 (Small).png
League of Legends 2014-06-06 02-58-05-420 (Small).png
League of Legends 2014-06-06 02-53-10-034 (Small).png