After hooking a Survivor, THWACK! activates:

The next time you break a Breakable Wall or a Pallet, all Survivors within 28/30/32 meters of your location will scream and reveal their Aura for 4 seconds.

At the start of the Trial, 4 random Hooks are changed into Scourge Hooks:

The Auras of Scourge Hooks are revealed to you in white.
Each time a Survivor is hooked on a Scourge Hook, the following effects apply:

The Generator with the most Progression explodes, instantly losing 9/12/15 percent of its Progression and starting to regress.
Survivors repairing that Generator will scream, but not reveal their location.

Unlocks potential in ones aura reading ability.  Each time a generator is fully repaired, Survivors within 16 meters of the completed generator will be revealed for 5 seconds.  When the last generator is fully repaired, all the survivors auras are revealed for 10 seconds.

While you are chasing the Obsession, this perk activates.

Damaging generators and breaking walls or pallets gives you a 5percent Haste Status for 10 seconds.

 Whenever you hit the Survivor with the total most time in chase with a basic attack, they become the obsession.

After a generator is repaired, The Entity blocked the generator with the most progress for 30 seconds.  You see its white aura during this time.

Iron Maiden increases your Locker Search speed by 30/40/50 percent.
Survivors who exit a Locker suffer from the following afflictions:

Scream and reveal their location to you for 4 second.
Suffer from the Exposed Status Effect for 30 seconds.