Release date 24 August 2015 (Update)
Members Yes
Level 94
Book Ancient Curses
Drain rate 300 points per minute (1 point per 0.2 seconds)
Effect +15 Defence
+10% more Constitution
+3% damage reduction
+10% accuracy to Debilitate and Bash
Base regeneration doubled
Passive regeneration works in combat
Click animation for full size

Fortitude is a Seren prayer unlocked on completion of the quest The Light Within. It is a combat prayer for use by tanks, which boosts Defence by 15%, life points by 10 plus 10 for each constitution level in normal mode (1 plus 1 per level in legacy mode) capping at a boost of 1,000 life points, boosts hit chance of defensive abilities by 10%, adds +3% damage reduction, doubles base life point regeneration and allows regeneration in combat. The life point regeneration stacks with Constitution skillcape perk, and the life point boost stacks additively with the life point boosts from the thermal bath, bonfires, and life point boosting equipment.

Fortitude cannot be used in conjunction with any sap or leech curses, including turmoil and its variants.

Life regeneration

Passive regeneration is equivalent to 0.1% of your maximum life points.

At level 99 Constitution this will be 9 life points per 6 seconds. With fortitude this is doubled, and your maximum life points increase by roughly 10% resulting in 20 life points healed every 6 seconds. This stacks additively with other similar effects like the regen bracelet which triples life point regeneration. If worn with the regen bracelet, with fortitude activated this would be a 5 times natural regeneration increase, or 50 life points for every 6 seconds. This is with no other additive increases. With full player-owned ports equipment added as well, and other life point boosting high-level gear, a player can easily reach between 13,000 and 14,000 life points, giving them a base regeneration of 14 added with the effect, healing 70 life points for every 6 seconds. Although this may seem negligible the targets in these high-level tanking gear setups have extremely high damage reduction, some with a base damage reduction as high as 87% in player-versus-player combat, and with achto gear, amulet of souls, and a tier 90 shield equipped, up to 89.1% damage reduction against a single style without use of abilities in player-versus-monster combat. A blow of 5,000 would be reduced to as low as 650 to 1,300 damage. This extreme tanking makes every single life point worth several times its normal value.

15 life points on a tank is additively worth about the same as 100 life points on a power setup. The same scale can be used for the natural regeneration to explain its actual practicality. 70 life points every 6 seconds would be the same as healing 520 life points every 6 seconds in the corresponding level of power armour.

Since December 2016, the original use (as explained above) has become even more practical with the release of several new life point maxima, and regenerative items, pushing the new maximum life points up by another 370. With the addition of the skillcape perks, the Constitution cape can double natural regeneration, stacking with the regen bracelet, and Fortitude. This pushes the regeneration multiplier to a max of 6, allowing a player to heal up to 84 life points every 6 seconds. With somewhat high requirements a player can (with use of a passive Saradomin godsword) train or kill many high-level monsters without the use of food or potions.

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