circle completion to kill enemy

jordan.saia@gmail.com

i was wondering if there is a way in game salad to encircle an enemy object with the player object in a delayed tail thrust and destroy the enemy object.
My coding skills are very much beginner level and I haven't found a good solution to this. Any advice?
See attached video for inspiration:

Socks

The actual drawing of the line that encircles the enemy is pretty straightforward - it's working out how to detect whether the enemy is within that area that might be tricky . . . .