I'm assuming your player controled bounding unit is a tradtional zergling and owned by player 1.
Make sure there is only ONE zergling on the map.
Trigger 1 (Player 1)
- should be to center a 2x2 location around the zergling. Preserve Trigger.
Trigger 2 (Player 1)
- If 'foes' brings at least one unit to the 2x2 location, kill the zergling
You may want to change 'foes' to something else, but this is basically the theory. It should work.