Each injured, dying, or hooked Survivor afflicts Survivors with a stack-able 1/1.5/2 percent Action Speed penalty to Repairing, Sabotaging, and Cleansing, up to a maximum of 4/6/8 percent.
Increases the Action Speed penalty by a further 12 percent, if there are 4 Survivors, who are either injured, dying, or hooked at the same time.

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.

You hear the sporadic whispers of the Entity whenever at least one Survivor is within 48/40/32 meters of your location.

While carrying a Survivor, increase your Carrying Movement speed by 6/12/18percent.  Increases your Terror Radius by 12 meters.