DRAGON QUEST BUILDERS

You will defeat more than enough monsters along your journey, don't worry about this as it will pop naturally.

All monster kills are saved to your profile in the background straight away, no need to save. Kills will transfer between all saves since they are saved on your Profile.

If this hasn't popped for the time you have acquired the rest of the trophies, load your save from the end of Chapter 1. Then equip some armour that improves your movement speed and your strongest sword, then keep running around the starting area killing Blue Slimes/Drackies. You shouldn't have many kills left so this won't take long. Or do this on a save from the end of the Final Chapter. You can use the Sword of Kings here that doesn't degrade so you won't have to worry about weapon durability. Then equip armour that improves your movement speed and kill enemies around the base, preferably the Orange Slimes and the Red Hands as they're the weakest.