Mass Effect 3
68 Achievements
Team Player
Infiltrate an enemy stronghold with your crew.
How to unlock the Team Player achievement in Mass Effect 3 - Definitive Guide
This achievement is not missable and unlocks after the third mission. Once Glyph helps you out the achievement will unlock.
Video below shows mission length and contains MASSIVE spoilers.
During the third mission, you will be tasked with infiltrating the citadel archives. Upon arrival, you will be attacked by 'someone' and have to fight your way out of the ambush and through the archives, in pursuit of your attacker. Upon catching up to your attacker and completing the mission, the achievement will unlock.
Story related, cannot be missed.
Story related. If you want more info, continue reading. Otherwise, know that this will unlock through the natural progression of the story.
When you're back in the apartment, speak to Brooks to start this mission. This mission makes up for the lack of combat in the previous mission. It's a straight fight with numerous mercs. Make your way through the Citadel archives, killing the mercs as you go. Early on, you'll see who you're up against and what the stakes will be. After a final confrontation and a call to Liara's bot Glyph, this trophy will unlock.