Transient Fortitude is a mode in Warframe that will significantly increase ability strength at the cost of ability duration. It is ideal on Warframes that have abilities that do not have any duration, either quickly finishing after the cast, or that can be toggled on and off.
To get Transient Fortitude, you need to open Orokin Vaults. Orokin Vaults in Warframe are hidden rooms in Orokin Derelict missions that contain rare mods. They can only be opened with a Dragon Key, and are marked by an intricate and ornate door. There are four different types of Dragon Key, and the doors will only open to one key, which is random for each door. The standard way to run Orokin Vaults is with a full squad, with each person carrying a different Dragon Key in their Gear Wheel.
When you find the Vault and open the door, you can get a special drop, which can be Transient Fortitude. If you are a solo player, it is a good idea to look for a group that is running the Orokin Vaults in the Recruiting Chat, as having a full squad searching the levels makes it much quicker to track down the Vault.
Transient Fortitude Stats
|Rank||Ability Strength||Ability Duration||Mod Capacity Cost|
|0||+5 percent||-2.5 percent||6|
|1||+10 percent||-5 percent||7|
|2||+15 percent||-7.5 percent||8|
|3||+20 percent||-10 percent||9|
|4||+25 percent||-12.5 percent||10|
|5||+30 percent||-15 percent||11|
|6||+35 percent||-17.5 percent||12|
|7||+40 percent||-20 percent||13|
|8||+45 percent||-22.5 percent||14|
|9||+50 percent||-25 percent||15|
|10||+55 percent||-27.5 percent||16|
Transient Fortitude can be stacked with other ability strength and ability duration mods to increase the bonus to strength and negate the reduction in duration. Mods such as Intensify, Augur Secrets, or Blind Range will add more strength, while Continuity and Constitution mods will reduce the impact of ability duration.