Keep getting one shotted in Shattered Realm as an Infiltrator (ultimate)

https://preview.redd.it/sdtsvfw1qqce1.png?width=1224&format=png&auto=webp&s=daa45c9e59e76900274b1a69c7e68cb1440b96f6

https://preview.redd.it/4einhcn4qqce1.png?width=1237&format=png&auto=webp&s=a5f7536c6305955ec8abae6080434c72ccd1abfe

https://preview.redd.it/kozb2dc6qqce1.png?width=1234&format=png&auto=webp&s=ea7245bec4504181668ee68ed4dc9d303d7fc723

This is my first character, everytime i meet the skeleton summoning boss, or the nightblade boss, im getting one-shotted. Help me fix my build pls.
https://www.grimtools.com/calc/O2GvYd6N