During the main case "Quid Pro Quo" is where you get the chance to earn this trophy. During the case you will go to Oakmont University in Reed Heights and acquire another location called the Department of Medicine. Here you will enter and see Samuel and before you can proceed further he would like you to clear the basement of the monsters inside. While in the basement you will find a large red button on the wall by the sink and another door you can enter. Examine this button three times and the large monster that is dormant in the other room will awaken netting you the trophy. Be warned that this monster will eat up a lot of ammo to kill and you still earn the trophy if you just let the monster kill you and reset the area. I recommend grenades if you have them!
*Some players have said that this trophy can be earned later as pressing the button and awakening the monster is not required to clear the basement and progress the case, thiis way the player has access to more powerful guns to take down the beast*