How to give node sillouhette when behind wall

I am working on a boss-rush fps game. I want it to be like the eye of cthulu fight from terraria, with the enemy flying towards you and then turning around to try again if it misses. However, in order for that to work, the enemy must be visible when they are under the ground. How could I accomplish this? I took this image from a post about a similar question, but for Unity, not Godot.