This trophy is story related, and will unlock during the normal progression of the game. You will get this upon successfully recruiting Mordin to your team, and if you want more information, please read the spoiler below.
*** Spoiler - click to reveal ***Mordin is one of the first teammates you are to recruit, as from the dossiers from the Illusive Man. He is located on Omega, and upon arrival, you are directed to speak with Aria at Afterlife.
She will tell you he is located in the quarantine zone, attempting to cure a plague. Head over there, and you will have to first talk your way past a guard, then fight through several groups of mercenaries.
Upon entering the clinic and meeting Mordin, he will ask you to spread the cure through the ventilation system before he leaves, and ask you to find his assistant. The ventilation system has however been shutdown by more mercs, so you will have to fihgt your way there.
Mordin's assistant (optional assignment) can be found in the left room, before entering the ventilation area. Once in the ventilation room, you will have to fight through waves of bad guys as you turn the system on, and then each fan.
Once complete, you will be back at the clinic. If you saved his assistant, he will be there, but regardless Mordin joins you anyway.
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