Section 8: Prejudice

As soon as level 3 starts you will come across a building where a cut scene starts. The cut scene shows a door that blows up and two mechs come through. This part of the game is actually where mortars are unlocked, so this is a perfect farming spot. Simply shoot away the mech’s shielding, call a mortar on it, and once both are gone restart the level; after you’ve blown up the fifth mech the trophy is yours.