Physical Resistance Rating

Overview
Physical Resistance Rating (abbreviated PRR) is a form of damage mitigation that was introduced with Update 14.

It provides a percentage reduction in physical damage (bludgeoning, slashing, and piercing), and is granted through multiple sources (items, feats, enhancements) and stacks with itself. Multiple effects granting an Enhancement bonus to Physical Resistance do not stack. Character sheets show the Physical Resistance Rating of the player next to the elemental resistances.

PRR is applied after damage reduction. The PRR is applied to the damage that passes through the DR and is always rounded down. As such If a player would take 20 damage before DR or PRR and has 10 DR and 60 PRR (37.5% reduction), the result is:
 * (20 - 10) * 37.5% = 3.75 rounded down to 3
 * 3 damage is resisted

Formula
The formula for calculating damage mitigation for physical damage was changed in Update 23. The new formula is: 100/(100+Rating). Incoming damage is multiplied by this number.

Example: A character is hit for 100 points of damage.
 * 0 PRR takes full damage, 100 points.
 * 20 PRR takes 16.67% less damage, 83 points.
 * 100 PRR takes 50% less damage, 50 points.

In effect, this means that for every point of PRR that you gain, your effective hit points is increased by 1%. This is entirely off of the base, rather than cumulative, and thus beyond a certain point, hit points might be more valuable that PRR alone...

Items

 * Armor proficiency provides a BAB-based bonus to Physical Resistance Rating when wearing armor. Without proficiency, base armor does not provide any PRR (although item affixes still apply).
 * Warforged/Bladeforged Plating feats provide PRR whether you wear a docent or not.
 * Regardless of proficiency, Shields always provide PRR (and MRR).
 * PRR and MRR multiplier: Wearing a large or tower shield double your effective PRR and MRR vs effects that require a Reflex saving throw. Doubling your PRR or MRR reduces incoming damage by a higher percentage as your base PRR increases - e.g. doubling 100 PRR reduces incoming damage by 33%, but doubling 200 PRR reduces incoming damage by 40%)


 * Note: Stacks with the Sheltering enhancement


 * See Category:Sheltering items
 * Enhancement bonus:
 * items with the Sheltering enchantment (up to +45)
 * items augmented with a Sapphire of Physical Resistance (up to +32)
 * Slave Lords Crafting items: Prefix(Blue) slot can have +12 (Heroic) or +33 (Legendary) Sheltering augment
 * Artifact bonus:
 * Planar Focus of Prowess grants +15 PRR when in a set with a Planar Conflux.
 * Slave Lords Crafting: Slave's Endurance Set Bonus grants +1/+2 PRR (Heroic) or +2/+4 PRR (Legendary). Values are for 3-piece/5-piece sets.
 * Ravenloft item sets
 * Insight bonus:
 * item with Insightful Sheltering (such as, up to +5)
 * item with Insightful Physical Sheltering (up to +22)
 * Quality bonus:
 * item with Quality Physical Sheltering (up to +11)
 * Luck bonus: Unbreakable Adamancy set bonus, +5
 * Mythic bonus: Mythic Boost items (on armor, shield, boots, back, head, neck, wrist), up to +4
 * Reaper bonus
 * Profane bonus:

Feats
Fighter
 * Heavy Armor Training +3
 * Heavy Armor Combatant +6
 * Heavy Armor Master +9
 * Heavy Armor Champion +12

Heroic
 * Ever Watchful - bonus equal to the number of Religious Lore feats you have, situationally
 * Greater Rage +10 when Barbarian raging in medium armor
 * Natural Fighting +4
 * Shield Mastery +3/+5/+10 when using a buckler or small shield / large shield / tower shield
 * Improved Shield Mastery +5/+10/+15
 * Two Weapon Defense +5 when you wield two weapons (not unarmed/handwraps)

Past lives
 * Past Life: Purple Dragon Knight: +3, stacks 3 times
 * Epic PL in Divine sphere: +3, stacks 3 times per type, up to +36

Destiny
 * Deific Warding +2, up to +20 situationally
 * Dreamscape +15 situationally
 * Guardian Angel +PRR equal to Wisdom score, situationally

Epic
 * Epic Damage Reduction +10

Legendary


 * Scion of Elysium +25 for summons / hirelings
 * Scion of Limbo +30 situationally
 * Scion of the Plane of Earth +20
 * Scion of the Plane of Fire +10

Monk stances
 * Lesser Mountain Stance +3
 * Mountain Stance +8
 * Greater Mountain Stance +12
 * Ultimate Mountain Stance +15

Acolyte of the Skin enhancements

 * Fiendish Form V +3 per Core ability in tree (already +15 when taken), max +18
 * Resilience of Body +2/+4/+6
 * Devil's Bulwark II +1 per 2 Warlock levels, up to +10

Bladeforged enhancements

 * Communion of Warding +4/+8/+12 Physical Resistance Rating

Deep Gnome enhancements

 * Hardy Nature +1/+2/+3

Dragonborn enhancements

 * Harder Scales +2/+4/+6

Deepwood Stalker enhancements

 * Survivalist I-III: up to +12 in light armor

Eldritch Knight enhancements

 * Improved Shield improves the Physical Resistance Rating by 3/6/10 while under the effects of the Shield spell.

Enlightened Spirit enhancements

 * Resilience of Body +2/+4/+6
 * Spiritual Bastion +3/+6/+10 to yourself while Aura form Blast is active, and additional +1/+2/+3 to yourself and nearby allies

Henshin Mystic enhancements

 * Each core enhancement grants +3 PRR.

Pale Master enhancements

 * Shroud of the Zombie: +3
 * Undead Augmentation (Deathly Touch): +5 while in any Pale Shroud
 * Eternal Furor: +15 while in any Pale Shroud
 * Ascendant Shroud: +10 while in Shroud of the Zombie

Ravager enhancements

 * Ritual Scarring improves the Physical Resistance Rating by 1/2/3.

Sacred Defender enhancements

 * Sacred Defense: +10 Physical Resistance
 * Improved Sacred Defense - Durable Defense: When in Sacred Defense, you gain +5/+10/+15 Sacred bonus to Physical Resistance Rating.
 * Redemption: +5 Physical Resistance
 * Glorious Stand: +5 Physical Resistance
 * Eternal Defender: +5 Physical Resistance
 * Harbored by Light: You gain +10/15/25 Physical Resistance Rating.

Shintao enhancements

 * Iron Skin improves the Physical Resistance Rating by 5/10/20.
 * Meditation of War improves the Physical Resistance Rating while under Mountain Stance by 10.

Sorcerer (elemental form)

 * Elemental Apotheosis: Fire, Air, Water: +20
 * Elemental Apotheosis: Earth: +25

Stalwart Defender enhancements

 * Stalwart Defense stance improves the Physical Resistance Rating by 10.
 * Improved Stalwart Defense - Durable Defense improves the Physical Resistance Rating while on Stalwart Defense Stance by additional 5/10/15.

Tempest enhancements

 * Cores: 2+1+1+1+1+1
 * Dervish (capstone): +10
 * Improved Defense: +1/2/3
 * Improved Parry: +3/6/10 while dual-wielding. (This bonus does not apply when fighting unarmed/with handwraps).

Thief-Acrobat enhancements

 * Spinning Staff Wall: Activate to gain 50 PRR for 20 seconds. Cooldown: 90 seconds.

Warchanter enhancements

 * Rough and Ready improves the Physical Resistance Rating by 2/4/6.
 * Ironskin Chant provides +6 Music bonus to everyone around
 * Warmaster (capstone): +15 Music bonus to single ally

Warforged enhancements

 * Adamantine Durability +4/+8/+12 Physical Resistance Rating
 * Memories of the Last War: +8 Determination bonus

Warpriest enhancements

 * Wall of Steel +3/+6/+10 Physical Resistance Rating
 * Sanctuary For 20 seconds, you gain +20 Sacred bonus to Physical Resistance. (Activation Cost: 10 Spell Points. Cooldown: 1 minute)

Wood Elf enhancements

 * Forest Origins: Oath of the Wild: You take an oath to forego metal armor, metal shields, and Rune Arms. As long as you do not have these equipped, you gain +10 Physical Resistance Rating.

Renegade Mastermaker enhancements
 * Supporting Construction: +2/4/6 Physical Resistance Rating
 * Action Boost Defence: +5/10/15 Action Boost bonus to Armor Class and Physical Resistance rating for 20 seconds

Epic Destinies

 * Audience with the Queen (Shiradi Champion tier 6): up to +100 situational
 * Damage Reduction (Fury of the Wild tier 2): up to +6
 * Ephemeral Evolution (Primal Avatar tier 1): up to +15 situational
 * Heavenly Presence (Divine Crusader tier 5): +10
 * Heed No Pain (Unyielding Sentinel 4th core): +10 and extra +20 while in Unbreakable stance
 * Improved Combat Expertise (Legendary Dreadnought tier 2): +20 when Combat Expertise is active
 * Legendary Shield Mastery (Unyielding Sentinel tier 2): up to +15 when wearing a shield
 * Master's Blitz (Legendary Dreadnought tier 6): +30
 * Sigil of Spell Warding (Magister tier 1): +15
 * Standing with Stone (Grandmaster of Flowers tier 4): up to +15 when in Mountain stance

Monsters with PRR
Monsters usually don't have PRR. Some enemies in the newer content have PRR, such as Abishai or Erinyes.

The increase in player damage from negative PRR uses the formula
 * damage increase = (100 + debuff) / 100.

For example, against a target with -10 PRR you deal +10% damage.

Player characters have a few options for reducing enemy PRR, for example:
 * Banishing Arrows: -1 PRR/MRR, stacks up to 25 times, 5 stacks fade away every 3 seconds. (for outsider enemies only)
 * Devour the Soul: -20 PRR/MRR, doesn't stack with itself, lasts 6 seconds.
 * Melted Armor debuff: -10 PRR and MRR, doesn't stack with itself, lasts 12 seconds.
 * Constricting Nightmare, enchantment on
 * Legendary Ooze weapon
 * Soul Tear debuff: -7 PRR and -20 hamp, stacks up to 5 times, lasts 11 seconds per stack.
 * Legendary Dust weapon
 * Shattered Device four piece set bonus: -10 PRR and MRR, lasts 10 seconds.
 * Taint the Aura: -2 SR, PRR and MRR, stacks up to 5 times, lasts 10 seconds per stack.
 * Taint the Aura: -2 SR, PRR and MRR, stacks up to 5 times, lasts 10 seconds per stack.

Tests: