There is a set of armor located at the second research lab, that once fully upgraded, is the most powerful armor in the game. The best part of this armor though, is that it allows you to stand up to those walking spider death lasers than can run as fast as a cheetah known as guardians. Overall it will cost 6000 rupees, and a lot of ancient parts including 9 ancient cores. You find the second research lab by following the main story line btw.
Rupees can be hard to come buy, over all you will probably need between 10k-15k rupees to be able to get this armor. 6k for the armor, and the rest for ancient arrows. Lets start with how to get the rupees.
There really are two ways to get the rupees in this game. One way is grindy and long. The other way is not as grindy, but kinda cheaty. Its your preference on how to go about this.
The non-cheaty way is to climb mountains and collect ore, hunt and cook dishes, or pay to play with amiibos. You can sell the ore and food for a decent amount. But you will be running around for a while trying to get enough. (Not my style at all)
The cheaty way is to head to the south east part of the map to a village on the beach called Laranue (i think thats how you spell it). In this village is a place to gamble. You pay 100 rupees, and pick 1 of 3 chest. In 2 of these chests is one rupee, in 1 chest is 300 rupees. The easiest was to grind this is to pick one chest and stay with it throughout the entire processes. You save the game, pay the man, and play. If you win, you save again and play again. If you lose, you reload the game and try again. It took me about 30 minutes to get 5000 rupees. This is a solution to the rupee issue.
The next issue is how to get the obscene amount of ancient gear needed to make the armor. The solution is to go to the second research lab, and buy ancient arrows (these cost a lot). Once you have a few, its time to hunt. These arrows, when shot in the eye of the guardians, one hits them (in most cases) (REVENGE!!!). When a guardian dies, it drops a huge amount of ancient gear. After about 5 of these, you will be close to having enough for 1 piece of gear. The hardest part about this, is getting the ancient cores. These are suoer rare, the the drop rate is low. As you play, keep track of where you see the guardians, and return when you have ancient arrows.
It took me about 1 hour of grinding to get 1 piece of armor. After, i was pretty tired so i played the game a little bit, and returned later to finish. You may be saying "that is a lot of work for some armor". But this isn't just some armor. This armor, once fully upgraded, is op AF. Once fully upgraded, it offers the highest defense of the game. It also has super resistence to the guardians, making it easier to fight them. The set bonus gives all ancient weapons you wield increase damage. And the ancient weapons are some of the most powerful weapons in the game. If your like me, I want Link to have the best, most over powered gear. I am ok with some grinding to do that. This armor is the new best thing since sliced bread, and is worth the grind (to me).
So there you go, happy hunting!