Go for the elemental patches on its arms and belly first. Getting rid of those will severely reduce its long and short-range attacks. I’ve found that the Rattlers Ice Bolts are good at this making the fight much easier. Like you have knocked all four feet off a rock breaker easily. This should be obvious if you are playing ultra hard but, never stop moving you stop and you could get hit.
It's been a while since I’ve beaten the fire claw but if you can, set up as many traps as you can (the blast and shock ones) manually or the trip caster. you can get stagers or even a knockdown. Use the ice thrower and use shock arrows to hit as many of the shock canisters on its butt as you can. I must admit I never tried tying it down so that might help.
Above all persevere, think about how you died and ways to prevent it, and do your best to think of your strategies and what works for you.
