This trophy is pretty simple to get on Operation Self Destructive on Normal. The Op starts outside of a tower, stick the enemy walking away from you and wait for him to blow up. The door will open directly in front of you, wait for the soldiers to split up, and shoot one in the leg. He'll immediatley stand up in a daze, use this opportunity to stick him with a Semtex. When he blows up, find another enemy in the direct area and do the same thing. Be aware that there are two baddies in the area above where you are, so take them out if you have to. Once you're done in this area, the next area will have a soldier running away from you. Use the same technique, being careful not to miss. Continue until you've stuck 5 enemies, and the trophy should unlock. Be aware, though, that collateral kills do not count towards your total.