Legacy Ice Crash slayer dies a lot

Greetings fellow players, I am Mails a returning and noob player just 200 hours in the game and still feel like not knowing much. I am playing in standard an ice crash slayer based on an old legacy mathlification build. Here is the link to my path of building https://pastebin.com/SqMwW37f I guess the build is outdated and as soon as the new betrayal league arrives i will play a new character so no biggy here. Still it amazes me that sometimes depending on map mods i get one shotted even in T8 maps. Today fairgraves killed me in Mao Kun and i was shocked. I have cleared up to T13 maps and it seems to me that sometimes you get a bad mix of monster mods and the monsters just kill you. Is there something in specific in the build i am playing that is weak?

My understanding is i have capped elemental resistances and 12% chaos, >5000 life and 6500 armor 35% physical reduction. So can anyone please ellaborate, share some insights and educate me as to how defence works? I really dont like dying, i find the 10% loss in XP severely punishing. Thank you for your time any response is appreciated.

Missing some details here, but I think the TL;DR is "you aren't meant to facetank every ability in the game". Especially, as you said, under certain combinations of map mods.

Thank you so much for your reply. What do you think about the seemingly random bursts of damage that you practically get marginal reaction time against? I mean i can surely understand I am not supposed to facetank certain attacks/effects, but i literally get seemingly one shotted quite a few times and i find frustrating because of the 10% penalty. I love souls game so i like the aspect of get good in path of exile during bosses, if i may say so, but how can i get good at dodging random bursts tha one shot me?