Need Help With SF Lacerate Slayer's Defences.

Been a long time since I've done an armour build. Still leveling and gearing right now, but I need help with defenses end game. Last time I made one, I distinctly remember that although I had high hp pool, my phys dmg reduction was crap. I couldn't afford more upgrades than what I had though and just self cast enduring cry (which I loathe).

Can anyone help me with advice and/or experience?

I was thinking maybe specing out of blood magic, buying a brass dome and running Iron reflexes, grace, determination (with enlighten of course). Would that be a good idea? I know armour is crap for big hits and has diminishing returns (or what ever), but what else can I do? Or would maybe brass dome and tri purity work (taking what ever measures I need to take to run tri purity).

I ask all this because eventually I want to take on Shaper.

I'm too used to being evasion + dodge + chest armour with gimmick (coil, kintsugi, perfect frorm+AA). My starter for league was Frost Blades Raider and it took way more punishment than my Slayer is right now, granted my gear didn't suck a**. Still though.