Performing a Chain
In order to get a chain of two or more together, you have to kill enemies that are from the same classification. You can check the classification of an enemy you already encountered by going to the Clan Primer on the menu screen and then the Bestiary.
The chain will break if you kill an enemy from a different classification or if you use the save crystal to heal/save.
The best location we found for this trophy early on in the game is at the Great Central Passage at Barheim Passage. What make this area great is that you will get to fight eight Skeleton enemies during each run. Not to mention that you also have an extra guest party member that will make the fights easier.
Once you get to that point of the story, there are a few preparations that you must do before you can begin the process of earning The Unrelenting. The first is to kill the Mimic sucking out the batteries at both the Great Central Passage as well as the zone directly south of it, The Zeviah Subterranean. Doing so would prevent the Spectre enemy from spawning. Although the Spectre and Skeleton are of the same classification, the Spectre takes a lot more time and effort to dispose of. If done correctly, you should have 46% charge remaining.
Don’t go beyond The Zeviah Subterranean as you will end up in a boss fight and automatically kick you out of the dungeon. Instead, backtrack to the aforementioned Great Central Passage.
Another precaution that you should take are the treasure chests in Great Central Passage. These are actually mimics, which are classified as an insect type. So it is best to avoid picking up the treasures (the mimics always spawn at the same spots) in that area when you are trophy hunting. If you somehow triggered the mimics, immediate hold R2 to flee and get out of the Great Central Passage zone as soon as possible.
The Skeletons alone should not give you any trouble if you made it this far already in the game. Keep in mind that you are fighting 50 enemies in a row without having to use the save crystal to heal your party. If you are having issues with the fights, try leveling up your character and spending LP on your license boards on HP and other stat boosts.
Once your preparations are complete, it’s time to start the 50-chain. Simply defeat the eight Skelton enemies in that area and then run back north to the North-South Junction and then north again to the Special Op Sector 3. Once you are at Special Op Sector 3, immediately head back south to the Great Central Passage again. You have to do this because enemies don’t respawn until you are two zones away in Final Fantasy XII.
It will only be a matter of time before you earn The Unrelenting trophy with this method. To further expedite the process, you can use Speed Mode via the L1 button on the DualShock 4 (you can also set the multiplier to four times the normal speed from the config menu screen).