Magical Resistance Rating

Overview
Magical Resistance Rating (abbreviated MRR) is a form of damage mitigation was that introduced with Update 23.

It provides a percentage reduction in magical damage acid, sonic, fire, electric, cold, alignment, light, positive, negative, poison, and rust), and is granted through multiple sources (items, feats, enhancements) and stacks with itself. Multiple effects granting an Enhancement bonus to Magical Resistance do not stack. Character sheets show the Magical Resistance Rating of the player next to the elemental resistances.

MRR is applied after resistances (If a player would take 20 damage before resists or MRR and has 60 MRR (62.5% reduction) and 10 resistance, the MRR is applied to the damage that passes through the resistance. The result is: (20 - 10) * 37.5% = 3.75. This is rounded down to 3 damage).

Formula
100/(100+Rating)

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

Items

 * Magical Resistance Rating offered by armor type:
 * Robes or Outfits: No MRR
 * Light Armor: 15 MRR
 * Medium Armor: 30 MRR
 * Heavy Armor: 45 MRR
 * Magical Resistance Ratings offered by shield type:
 * Buckler: No MRR
 * Light Shield: 5 MRR
 * Heavy Shield: 10 MRR
 * Tower Shield: 15 MRR
 * Enhancement bonus: items with the Sheltering enchantment