Not sure if it would look good, but based on the picture shown, you could try making an orbital movement.
You will need:
-Origin point //Image point on the enemy ( user for the ball to orbit around)
On an every tick event position the ball using the following:
local variable "rad"(radians) = angle * (Math.PI / 180) // here we convert the angle to radians
ball> set X> origin.x + radius * Math.cos(rad)
ball> set Y> origin.y + radius * Math.sin(rad)
angle > add value > speed // the angle variable is what defines the position of the ball..if you don't increase it the ball won't move
Another try, sync 2 sines behaviours, one horizontal and one vertical, could also give you this effect.