Iron Sky: Invasion

The "Alberich" is fairly common. They are stronger and have better armor than a Walkyr or Rheingold. They are also pretty fast. They are taken down with your any weapon, they have no countermeasures so you can use missiles or the standard gun. Simply take down 50 of them over the course of the game to unlock this trophy.

You can check how many you have destroyed by pressing  and then Statistics. The enemies you have killed will be listed in order from most to least.

All the trophies for destroying X amount of ships can be farmed, however the game creates a save for each individual chapter meaning when you load a previous save, your stats will reset to what they were when you've completed the chapter. If you follow the Roadmap you will not need to farm any of the kills, the majority will unlock during Chapters 3 & 4.

Remember to check your map with  if you want to actively seek them out.