Anyone do this before? The concept seems tanky, but are crab armours a thing? I never see any builds use them. If you want to choose your favorite build, don't forget to choose PoE currency purchase on U4GM.com.

RF Jugg already has incredible physical mitigations, the crab is just overkill. It's elemental damage that's gonna kill you. You should already be approaching the phys reduction cap (90%) against most hits. ~It might be better on LL RF guardian~ but I'm not really familiar with that version.

It would make you tankier against phys damage. At the cost of sacrificing kaom's heart or the AoE damage chest, and sacrificing kaom's roots if you use them, and sacrificing the best damage slot for RF (your helmet) (I really don't see the point of playing crab without those three items unless you are a ranged build that barely gets hit.) So no it doesn't seem like a good option for RF.

I have tried it because i saw a youtube budget righteous fire using it. After searching for it on poe.trade, it is amazing how cheap it is. Yet it provides so much phys damage reduction, resistance and armour. If you dont mind your dps being low but high survivability, you should give it a shot. I use it to run uber lab and you can tank all of his physical hits. Buying PoE currency and poe orbs cheap are always the easiest way to level up.

The crab stuff is pretty good. I used it on a lab runner. Its nothing amazeballs but it works. I don't see any particular synergy with RF in particular though. If you want to use the crab armor set in particular I'd just go with any Jugg attack build.