This trophy will once after you defeat the one and only boss at the end of the game. When the battle begins, you must destroy the generators that are placed around the room, you will also need to avoid the lasers that he shoots at you, they aren't hard to avoid as long as you see them coming as he's preparing the shot. There will also be enemies on the ground during this battle, not much of them though, so they're pretty easy to avoid. You can use any mining tool to destroy them.

Once you have destroyed them all, the electrical force field around the boss will disappear and you will have a chance to get on top of him and damage him as much as possible in the limited time that you have. Once he recovers, he will somehow magically grow generators back, reactivating his force field. You will need to destroy all the generators one more time then destroy the boss this time when his force field shuts down.
 

Assimilated - Final Boss Battle Video Guide