Fortification

Fortification represents a percentage chance to negate a critical hit or sneak attack. When a critical hit is negated, damage is applied normally rather than at the critical hit multiplier. Fortification items stack with racial fortification of Warforged. Two standard fortification items which provide enhancement bonuses to fortification do not stack. However, Exceptional Fortification items do stack with everything except themselves.

Since Update 13, monsters with sneak attack dice are able to bypass some of the player fortification equal to monsters' Challenge Rating. E.g.:
 * If a CR 1 Kobold Sneak attacks someone with 50% fortification, the Kobold Sneak has a 51% chance to normally conduct a critical hit or sneak attack.
 * If a CR 20 Lava Mephit attacks someone with 100% fortification, the Lava Mephit has a 20% chance to normally conduct a critical hit or sneak attack.
 * If a CR 54 Sellsword Footpad attacks someone with 150% fortification, the Sellsword Footpad has a 4% chance to normally conduct a critical hit or sneak attack.
 * If a CR 29 Earth Elemental attacks someone with 125% fortification, it is still going to have a 0% chance to critically hit or sneak attack, as it has no sneak attack dice.

Exceptional Fortification (10%)
Effect: Grants a +10% exceptional bonus to fortification, which protects against critical hits and sneak attacks. Exceptional bonuses stack with everything except another source of the exact same bonus.
 * Found on:
 * Toven's Hammer
 * Stalwart Trinket
 * Greater Stalwart Trinket
 * The Disciplinator
 * Sustaining Symbiont

Exceptional Fortification (25%)
Effect: Grants a +25% exceptional bonus to fortification, which protects against critical hits and sneak attacks. Exceptional bonuses stack with everything except another source of the exact same bonus.
 * Found on:
 * Omniscience

Exceptional Fortification (50%)
Effect: Grants a +50% exceptional bonus to fortification, which protects against critical hits and sneak attacks. Exceptional bonuses stack with everything except another source of the exact same bonus.
 * Found on:
 * Livewood Core (Level 24)
 * Leaves of the Forest (Level 24)

Construct Fortification (10%)
Effect: Grants a +10% insight bonus to fortification which protects against critical hits and sneak attacks. Insightful bonuses stack with everything except another sources of Insight bonus, only the highest Insight bonus is applied.
 * Found on:
 * Docent of the Claw
 * Dragontouched Docent
 * Quorforged Docent of Battle
 * Docent of the Flames
 * Quorforged Docent of Battle (unsuppressed)

Stacking Fortification (25%)
Effect: Grants a +25% stacking bonus to fortification, which protects against critical hits and sneak attacks.
 * Found on:
 * Fabricator's Bracers and Fabricator's Gauntlets worn as set, once Nearly Finished is unlocked.

Brace for Impact (+20%/+40%)
Effect: Passive Bonus: [+20/40]% fortification. +[1/2] reflex/fort/will saves. Tier 1 Epic Destiny ability that can be purchased twice for a total of 40% fortification. Bonus type unknown.
 * Found on
 * Unyielding Sentinel