Kill 100 Lutadore Enemies with explosives in the Campaign (Grenades, Rockets, Barrels)

You can unlock this one meanwhile you are playing the campaign, but if you need to farm it, select Chapter 11 Red Sky, Checkpoint: 04 Mine. Right at the start 6-7 enemies will start to run in front of you quickly select up on the d-padand choose the grenade, throw it and you can easily kill 6-7 right there. Reload the checkpoint, rise & repeat until the trophy pops OR you can try in another spot like this video shows it: