Underlying Defense Formulas

Armor Damage Reduction = Armor Value / (Armor Value × 10/9 + Constant) (Constant changes with level, ~5000 at level 60)

Resistance Damage Reduction = Resistance Value / (Resistance Value × 10/9 + Constant) (Constant changes with level, ~1000 at level 60)

Final Damage Taken = Raw Damage × (1 - Armor Reduction) × (1 - Resistance Reduction) × (1 - Other Reductions)...

(Note: The 5000 and 1000 in the formulas are the system's decay constants at character level 60.)

10/9. This number is Blizzard's shackle to prevent you from reaching 'invincible' status. No matter how massive your Armor or Resistance values get, after plugging into this formula, the max reduction caps out approaching 0.9 (90%). Guides endgame gearing hard.

I. How Damage Hits You (Defense's Three Lines)

Monster damage doesn't straight-up deduct from your life—it passes through three 'filter nets' first.

First Line: Armor

Current mechanics make Armor a 'flat reduction' against all damage (including elemental magic). It's your top priority frontline defense.

Sources: Gear and Paragon base Armor, plus massive Armor from Strength (1 Strength = 2 Armor).

90% Hard Cap: As the formula above shows, Armor's reduction is forever locked under 90%.

Second Line: Elemental Resistances

After monster damage gets shaved by Armor, the leftovers hit Resistances.

Sources: Gear and Paragon base Resistances, plus Intelligence baseline (1 Intelligence ≈ 0.4 All Res, rounded down on display).

Same Limit: Like Armor, single Resistance max reduction is hard-capped at 90% by the formula. Resistances cut damage from specific elements (like poison pools on the ground, fire mob explosions).

Third Line: Other Damage Reductions

Includes gear affixes like 'All Damage Reduction,' 'Fortified Damage Reduction,' 'Damage from Close Enemies Reduction,' etc. Uses multiplicative math—each only reduces the 'remaining damage' from prior steps. When gearing, one fat high-value reduction affix beats a bunch of tiny ones stacked together.

II. Damage Absorption Order

After peeling through these three lines, what's left is your true damage taken. System priority:

Barrier First: Premium buffer pool—while it's up, you're untouchable.

Fortify Next: Not just damage reduction when active, it's also your second health bar after Barrier breaks.

Life Last: Blood bar dropping means all frontlines are breached.

III. Toughness (EHP), 'Long Board' & 'Barrel Effect'

Don't judge a build's survivability by panel life—check EHP (Effective Hit Points).

EHP logic: EHP = Max Life ÷ Final Damage Taken Ratio. Example: If Armor, Resistances, and reductions drop monster damage to 10% (90% total mitigation), even 15k life needs 150k raw damage to one-shot you!

'Long Board' & 'Barrel Effect': Tweak for scenario damage types to boost 'one-shot threshold'.

IV. Practical Anti-One-Shot Tips

With these mechanics down, gearing gets straightforward:

Don't tunnel single stats: Armor/Resistances cap at 90%—hit benchmarks, then slot other reductions.

Stack Life: Hunt 'Maximum Life' affixes relentlessly. Life is EHP's foundation—longer bar amplifies all your mitigations.

Extra Lines: Max out Barrier, Fortify, Block via skills or aspects—they skyrocket your margin for error.

Hope this helps. Stay alive to DPS—stand firm, farm hard!