In Horizon Zero Dawn there is an armor which is basically the most overpowered armor in the entire game. The reason this armor is the best is that it can take a direct hit from a Stormbird or even a Thunderjaw and you won't lose any health. Now, how do you find such an armor, if you've played the Ancient Armory side quest then you may already know that you have to gather power cells in order to get the suit and then later solve a puzzle. This requires you to go to certain locations in order to find the armor. The first location is in All Mother, the place where you go after you complete The Proving. All you have to do is look for a vent and when you reach the end, you will come to a room and you can just pick it up.
The second location is at Maker's End and basically, there is a quest which requires you to go there and you can just go to the highest point of the tower and you'll find it there. The third location is Grave Hoard and you have to go there for a quest as well so you just have to follow the directions. The fourth location is GAIA Prime, the quest The Mountain That Fell will take you there and you have to really look for this one. The last location is The Ruins where you will find frozen icicles blocking the path to a door and all you have to do is break it using R1 or R2, the power cell will be inside. In order to obtain the armor you have to activate the side quest Ancient Armory and it will take you to the location. Enjoy!