After repairing Generators for a total of 70/60/50 percent, Flashbang activates:

Enter a Locker while empty-handed and press the Ability button to craft a Flash Grenade.
The Flashbang is left behind when escaping the Trial.

Prevents Crows from being alerted by your proximity and flying off, unless they are being stepped on.
Suppresses the urge to scream from any cause at all times.
Suppresses all noises related to unlocking Chests, and cleansing or blessing Totems.
Reduces their Interaction speed by 40/35/30 percent.

Whenever you become injured, you retain the Movement Speed burst for 2 additional seconds.
Overcome causes the Exhausted Status Effect for 60/50/40 seconds.
Overcome cannot be used when Exhausted.

Increases your Altruistic Healing speed by 100 percent for the next 30/60/90 seconds whenever you rescue another Survivor from a Hook.

You refuse to fail, even during your darkest hour.
Increases your Action speeds in Healing and Unhooking by 10/12/14 percent for each injured, hooked, or dying Survivor, up to a maximum of 40/48/56 percent.

Unlocks potential in your Aura-reading ability:
Paranoia paired with your horror of failure helps prepare you from repeating the same mistakes.

The Auras of the 3 Generators in closest proximity to one another are revealed to you for 30/45/60 seconds at the start of the Trial, and each time a Generator is completed.
Increases your Repair speed on those Generators by +5 percent while active.
If you are holding a Map, all Generators revealed by Déjà Vu are automatically added to it.