What is this effect called and how to make something like this ?

I’m talking about the blue spell. I understand how to make the ball in the center but how do you do that thing on the ground to be aligned perfectly to the ground ?
An other example would be the green circles that appears when you try to cast ranged aoe spell in wow, gw2 etc

That is probably done with decals… or at least, how you could do it inside ue4.