Adamantoise is the hardest boss in Final Fantasy XV with tons of HP. It takes more than 30 minutes to kill it normally and 15 minutes if you use a food item that boosts your criticals.
However, with the new update that adds chapter 13 cutscenes, we also have a ring of Lucii buff that can kill enemies in one hit when you press R1 and Triangle button.
Thing is, now it can work with the Adamantoise as well. It does take a lot of tries to actually get the RNG to roll in your favour though.
Here’s a video of the ring in action which has been buffed. Our review gave it an 8.5/10.