Mass Effect 3
This achievement is story related, unmissable. When getting to Priority: Thessia, the asari homeworld, you'll fight once again Reaper forces while trying to make progress on your Prothean investigation.
*** Spoiler - click to reveal ***Here, you will take Liara as a companion while seeing how the asari forces are being outnumbered by the Reapers, also fighting again with Kai Leng in your second encounter in the game.