There are many defensive unique items you can use in your build. I will be listing a few of them below. These vary in price depending on the popularity of the builds they are mainly used in.
Bringer of Rain – This is one of the most iconic unique items in Path of Exile. When released, it gave you a 7 link, block, and 200+ life. It was then nerfed twice. It still remains one of the most power options for melee builds that utilize block. It’s only downside is that it doesn’t allow a chest to be worn.
Lightning Coil – Again, an iconic item of Path of Exile, this lets you take 30% of your physical damage as lightning damage (40% with legacy). Pair this with 75% lightning res or even more and you get a solid defensive chest to help mitigate physical damage. The only downside is – 60% lightning resistances but this can be made up for with other gear.
Rumi’s Concoction – This flask provides block and spell block as well as some armor. Many builds combine this with pathfinder, flask effect nodes, and a shield, to get maximum block. This means running one flask can give you 75% chance to not take damage per hit.
Taste of Hate – This is another great flask although it is quite expensive in new leagues. It provides a 20-30% more damage boost to your physical damage as well. This flask also allows you to take 20% (30% for legacy) of your physical damage as cold damage. This makes it a psuedo lightning coil that only takes up one flask spot. Paired with pathfinder and some flask effect nodes, it becomes godly.
Belly of the Beast – This chest gives 30%-40% increased maximum life. This is amazing when you have a lot of flat life on other gear to scale it. This chest also drops often and is quite cheap unlike some other options given in this article.
Kaom’s Heart – This is one of the most famous items in Path of Exile history. It’s legacy variant goes for more than any non-perfect unique has ever gone for. Even the nerfed version provides 500 life. This works well when you have a lot of life scaling in your tree. If you have 200%, easily achievable on a melee build, then Kaom’s Heart adds 1500 life.