Using this blueprint I was able to spawn a sphere mask material at the impact location which then can reveal the enemy outline.

Sphere Mask material details : 

This material can be divided into 2 parts

1. Sphere mask which can draw an imaginary sphere in the world and using this sphere we can tell the material to reveal enemies in the selected area only. So I have used the sphere mask as the alpha of the lerp so we only reveal the enemies in the selected  area.

   Also in sphere mask I have exposed the radius and location as material parameter collection which then I used in the Blueprint to spawn the effect on the given location and I have animated the sphere mask radius using simple anim timeline.

2. Custom depth which checks if the mesh has the particular custom depth enabled or not, if yes it tints the mesh in red and renders it above everything (i.e we can see it through the walls and obstacles).