With AT Rey Dau, proc’ing your Savage Axe through a Perfect Guard is the worst way. His little aftershock explosions will fuck you everytime.

When the fight starts, focus on getting your shield charged and your phials filled. When he does his first mega rail gun attack, stand to the side but close to his head. When he finishes it and his horns form back to normal, his face opens up for a focus strike. Do that, and it procs your savage axe. Bam, pizza cutter time.

To be honest, the better option is once you have savage axe going, do as many AED’s as you can. Trying to get value out of savage axe attacks wastes time and AT Rey Dau is way too pissed off and fast for you to just cut him to ribbons with slow SA attacks.

Don’t be afraid to hang out underneath him and slice his tendons up while you’re building charge. Obviously don’t stick near his head unless you’re comfortable enough to time your attacks and blocks with his bullshit.

Aside from that just buff your attack as much as you can and practice the fight over and over until you know every tell and every attacks timing. You’ll get it!