at higher floors, no matter how much Health, armor, resist, or damage reduction you have, unless it is 100%, you will eventually get 1 hit dead by the monsters.
Barrier and Diffusion are Wizard Talents that make Manashield better, but it requires lots of MP and All Resist. and eventually, you will get to a floor where a monster 1 hits you dead even with a high defense Manashield.
eventually you will need Block & Dodge, and Sanctuary for survival, or some other way to get out of the way of getting hit.
maybe have an Explosive affix so that your Barrage has a chance for AoE effects, and use Storm for defense and monsters that get too close to you.
only a few Crystals can be used on Eternal Items, so they are harder to change when you need to change them. Legend Items are not as powerful as Eternal Items, but you can use all Crystals to change them.
Manashield needs MP, and you only have Hero Points in Strength. Health wont help you if your Mana is so low that it makes your Manashield as thin as paper.