The Last Guardian – Last-Minute Reprieve Trophy Guide – Have Trico defeat 20 or more suits of armour while they are carrying the boy. [Bronze]
During combat encounters the suits of armor will try to carry you away. If Trico is nearby he will come to your help and kill the enemy. The trick is to let the weak enemies grab you (brown armor). They die in one hit. The ones in white armor take 3 hits to kill and won’t die instantly.
A great farming spot for this is at the end of the game on your way up the last tower. Here you will have the two largest enemy encounters in the game. Let some enemies grab you near Trico and wait for him to kill them.
You can farm this via checkpoint restart! It can be done over multiple playthroughs. Your progress carries over into New Game+.