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.

3 seconds after injuring a Survivor by any means, Dissolution activates for 20 seconds.  While Dissolution is active, if a Survivor fast vaults over a pallet inside of your Terror Radius, The Entity will break the pallet at the end of the vault, and Dissolution deactivates.

You become obsessed with one Survivor.  Your Obsession gains a 33percent action speed bonus to unhooking and healing other Survivors.  Each time you hook a Survivor other than the Obsession, if the Obsession is alive, gain a token.  If the Obsession is alive, all Survivors who are not the Obsession get 3percent penalty to repair, healing and sabotage speeds for each token.

Two trapped Hex Totems will spawn in the Trial Grounds.
When either Hex Totem is cleansed or blessed, all Survivors suffer from the Exposed Status Effect for 40/50/60 seconds.
The second Hex Totem will immediately turn into a Dull Totem.

The Auras of Survivors within 2/3/4 meters of any Dull Totem are revealed to you.

When another Perks Hex Totem is cleansed or blessed, its Hex is transferred to the Hex: Undying Totem, including any accumulated Tokens, disabling Hex: Undying instead.
The Hex effects persist until its Hex Totem is cleansed.

When hooking a Survivor, all other injured Survivors suffer from the Hemorrhage and Exhaustion status effect for 45 seconds.

Blood Echo has a cooldown of 60 seconds.

Exhausted prevents survivors from activating exhausting perks.
Hemorrhage regressing healing progress when not healing, and increases blood trails left by injured survivors.