Getting 1 shooted

So i have max res , 13k armor 60 percent block , im playing gladiator, so at this stage i can do tier 9-10 maps , but ive been testing what is the thing im dying instantly and its a basic fireball from skeletons in crypt even tier 1 map , i just dont understand how is that possible , pls help.

You have 2000 life at level 89. You should have more than double that.