Good way to increase AR:
Plagued, Battlemage, Satyrs Spirit. Add 1700 AR or 2x of them. Also 9% AR or higher as epic affix. Hardened talent if you're warrior with hp stat point and 4+ Strength affix and you can include the 9% AR epic affix.
Lets say your build uses 2× 1700 AR, 75×4 AR wizard gears , 1× 4 Strength , 96% AR from Satyrs spirit from 256% Gold Find , 60% AR Battlemage and 75% AR Plagued.
1700+1700+300= 3700 AR. Strength 4 adds 2k AR so 5700 AR.
5700×1.96×1.75×1.6= 31,281.6 AR. As figured, the more AR the better in damage Reduction.
10000-(10000×31,281.6÷(31,281.6+20×1000) = 3,900.034320302 damage. In total, that's about 61% damage Reduction alone!
You can also use the protection nature but that's bugged as far as I know and it's better using the nature slots for luck or Satyrs spirit.
Good way to increase resist:
Fauns Gift, Cerebral Vortex, SpellSword , Ascendant , Elements and Cerebral Vortex. Realistically, people will use CV and Fauns Gift but you can have the option of Ascendant , spell sword and elements for a build. Also 4+Intelligence legend affix, blessed talent and a possible blessed nature if not luck nature for Fauns gift. However it's better off using Fauns gift in many cases.
There's a reason why Larrybird had some success with Ascendant but generally more AR is a better goal.
Also another note is that you have 60+ shock resist on gear if you put the element on chest, hat, ring, amulet, pet and trophy.
150+ All resist + 60 shock resist = 210 Shock resist altogether which is the most important protection value since a majority use shock.
Scenario: 150+ All resist, shock resist on gear , 112 shock resist epic affix , Fauns Gift and Cerebral Vortex. 96% increased Resist using 256% luck from Fauns gift. Also 4+ Intelligence affix. for 200 all resist.
150+200+60+112= 522 Shock Resist. 522×1.96×1.375= 1406.79 Shock Resist. The other resists are 943.25
10000-(10000×1406.79 ÷(1406.79 +20×100)= 5,870.6289498325 damage. The damage Reduced by resist alone was around 42%. Resists do definitely help even if you didn't plan on using Satyrs spirit build as not every build needs that. Sometimes better with more HP and attack with some reduction, combined with AR of course.
Other ways to reduce damage and add to overall damage Reduction: Hyper Armour , Defiant, Deadly Arts (for the damage build, it can actually give a lot of reduction but also for the purpose of deadly arts) , Pathfinder (not usually worth it but it does work with dodge) and Permafrost with MP Absorb .
Perserverance is also a great choice for damage Reduction and usually a no brainer for dot reduction. With high enough dmage reduction, even just 1× 40% damage Reduction can reduce dot to 80% damage reduced or more and 2× 40% Perseverance for even more. It's easy to see why you can make player deal 0 bleed, 100 bleed or 1000 bleed but not much bleed whatsoever. It definitely makes fire and poison useless sometimes.
Blistering will especially be affected far worse than normal bleed since fire can be nerfed by 40% from perserverance but the bleed from nerfed fire dot will be nerfed by a further 40% so basically more than 70% reduced damage or so to bleed.