Fortify

Fortification is a stackable buff that grants the player 1% less damage taken from hits, it has a maximum of 20 stacks and lasts 5 seconds. . The amount of stacks gained depends on a combination of the strength of the hit and the enemy's ailment threshold. This does not apply to damage over time, since it does not hit.

Sources of Fortification

Fortification can be gained by multiples sources which split into two categories, those that go through regular rules of fortification (Hit) and those that works as buff with a limited amount of Fortification. The sources are the following:

The Hits:

• Fortify Support is the most simple source, having no drawback. Advancing Fortress supports the skill gems with it
• The Fortify Mastery can also gives you Melee Hits Fortify but at the cost of -3 Maximum Fortification
• The Ascendant's Champion ascendancy passive skill gives Melee Hits have 50% chance to Fortify making it harder to keep the Fortification at its maximum
• Perseverance gives Melee Hits which stuns Fortify making it hard to keep the Fortification on bosses and impossible if they're immune to stun
• Overwhelming Odds doesn't have any drawback but only works with Cleave
• Vigilant Strike offers the only sources of fortification with a base duration of more than 5 seconds (8 seconds), the cost being that it has a cooldown, bypassable by expending an endurance charge

The Buffs

• The Champion's Fortitude ascendancy passive skill grants 20 Fortification.
• Kingmaker grants +10 Fortification to nearby allies.

Maximum Fortification stacks

Increasing the maximum Fortification by 80 stacks will provide 100% less damage taken from hits. Up to 63 stacks can be attained by combining all of the following:

• +15 stacks from Beacon of Madness, but only while affected by Glorious Madness status icon.pngGlorious Madness
• +10 stacks from the master crafted mod +10 to maximum Fortification while Focused, but only while you have Focus
• +10 stacks from a nearby Dread Banner, but only for a limited amount of time scalable with Perfidy and increased duration
• +6 stacks from 3 skill tree nodes including Steadfast, and 2 small skill nodes
• +3 stacks from the Fortify Mastery
• +3 stacks from a Penitent Mask helmet base type
• +2 stacks from dual-wielded Ichimonji coupled with Dread Banner
• Up to 14 stacks added to passives by the best known roll of Lethal Pride (need proof)

It's possible to reach 80+ in standard thanks to legacy items

Mechanics

#% less Damage taken modifiers are calculated after armour, resistances, and Endurance Charges.

You can also get a Fortify buff through an amulet anointment called Hardened Scars, which grants Fortify while recovering life from any life/hybrid flask.

The effects of Fortify are affected by increased Buff Effect, which can be obtained through Ichimonji (increased Buff Effect).