>>2163492
I've actually done a memebuild like that before to make kind of a pseudo Barbarian. It uses Lunatic Beast for 15 AT reduction when hit, Sword of Protection for 30 AT on block and Distorted Heart for 10 AT when copying an enemy's buff (which happens pretty much all the time in the lategame)
As you identified, getting to 33% HP without dying is kind of challenging. You could put Impulse Fields in to make it a lot more likely to safely get that low if you didn't bother with Distorted Heart and have 1 Defence slot to spare for something else. Second Heart maybe, which revives at 33% and guarantees that you come back in Final Resistance HP.
The build is very viable and it kicks ass in 58V which a lot of people consider to be a very annoying map.