EPTI'm covering my strategy in the "Spoiler" below.
+ Show Spoiler +
1) Location: The spot where i completed the achievement was about half way to the second Fissure Point. You'll recive a message from General Warfield right before reaching the location, the message is telling you to rescue a group of firebats and medics that are under attack by the zerg. Rescue the forces and then save your game before moving on.
2) Positions: You want to have as many Infested Terrans gathered at the same location as possible, therefor i decided to send all my reinforcements and heroes far behind to prevent them from taking part of combat or getting attention from any monsters. I used 1 Medic and Egon Stetmann to trigger the spawn event.
Once triggered i ran to the location where i rescued the firebats and positioned the Medic in the top left conor and Egon Stetmann as close to the Medic as possible. You'll have a wave of Infested Terrans hunting you down to this spot and they will try to attack your Medic since the medic has top attack priority. But if you are positioned correctly Egon Stetmann will block the path to the Medic and prevent the medic from being attacked. This allows the Infested Terrans to stack up in the room without causing any harm on your units.
3) Execution: Once all the waves of Infested Terrans have stopped spawning and reached the "room" where your Medic and Egon are located it's time to save the game. (See picture below) It's now time to move Jim Raynor to a good position and try to aim your Penetrator Round ability to hit as many units as possible. You must be ready to fire before too many of the Infested Terran leaves the room, otherwise you'll not be able to kill 50 targets in one shot. Decide a location to move to, then aim carefully and fire.
![[image loading]](http://img52.imageshack.us/img52/1192/screenshot2010073101503.jpg)
This is the ideal positioning that i used.
If you don't manage to earn the achievement at the first try you can simply reload the saved file and try again. Keep going until you succeed!
Good Luck!
2) Positions: You want to have as many Infested Terrans gathered at the same location as possible, therefor i decided to send all my reinforcements and heroes far behind to prevent them from taking part of combat or getting attention from any monsters. I used 1 Medic and Egon Stetmann to trigger the spawn event.
Once triggered i ran to the location where i rescued the firebats and positioned the Medic in the top left conor and Egon Stetmann as close to the Medic as possible. You'll have a wave of Infested Terrans hunting you down to this spot and they will try to attack your Medic since the medic has top attack priority. But if you are positioned correctly Egon Stetmann will block the path to the Medic and prevent the medic from being attacked. This allows the Infested Terrans to stack up in the room without causing any harm on your units.
3) Execution: Once all the waves of Infested Terrans have stopped spawning and reached the "room" where your Medic and Egon are located it's time to save the game. (See picture below) It's now time to move Jim Raynor to a good position and try to aim your Penetrator Round ability to hit as many units as possible. You must be ready to fire before too many of the Infested Terran leaves the room, otherwise you'll not be able to kill 50 targets in one shot. Decide a location to move to, then aim carefully and fire.
This is the ideal positioning that i used.
If you don't manage to earn the achievement at the first try you can simply reload the saved file and try again. Keep going until you succeed!
Good Luck!
Edit (2010/08/23): Added an old screenshot that i forgot to upload before
