I'm not a fan of using Shadow Wall on the first & third Plasmas. I prefer using Shadow Wall right after the first set of adds die & before the Gunnery Pod & Royal Fount go off.(to keep Grit off until second set of adds spawn) You should never take more than about 11k damage, so any VIT gear or shielding from the healers will keep you safe. I usually go 2STR/3VIT/Full STR attributes until content is on farm, I don't ever put on more VIT than that unless healers are noticeably struggling or ask.