Suturing Expert Trophy
Heal your fireteam with an aid kit 100 times.Note: The A.I teammates do count towards this.
To heal a teammate, you must have an aid kit in your possession then walk up to your injured friend and hold . There are only 2-3 aid kits per-mission and you can only carry 1 at any given time so choose carefully who and when you heal. The fastest way to grind this out is in Horde Mode, because aid kits drop/spawn there fairly frequently. Here's a farming method courtesy of enaysoft:
Start Horde mode on Intense difficulty. There are some aid kits just scattered around the level so find each of them then shoot the AI in the head, heal - rinse and repeat until you run out of aid kits, then let yourself die. Rinse and repeat this trick until you have the trophy.