Kill 10 enemies or drones while affected by a sonic blast.

The assault exo has this ability. All you need to do is press [ Register or Signin to view external links. ] and any enemies nearby will put their hands to their ears and be stunned for a short period of time. Simply shoot them when they are in this state and it will count towards one of the ten. This trophy is very easy as you can farm it, so if you die or restart checkpoint the kills will still count. Getting 10 kills is very quick, so if you really want to you can do this to the first few enemies you encounter when you start the game.

A perfect opportunity to earn this trophy, is during the 9th mission "Crash". There are lots of enemies at the start so just go around using the sonic blast and killing enemies until the trophy unlocks.