You become obsessed with one Survivor.  When the Obsession loses a health state, your Terror Radius transfers to the Obsession for 30 seconds, and its radius is set to 32 meters.

You are granted the Undetectable status effect for the duration.

The Survivor with the transferred Terror Radius is also considered to be "inside the Terror Radius" for other purposes.

The Killer can only be obsessed with one Survivor at a time.  Undetectable hides the Killers aura, Terror Radius, and Red Stain.

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.

Increases the volume of Survivors Grunts of Pain by 25/50/50 percent.
Increases the volume of Survivors regular breathing by 0/0/25 percent.

Survivors within your Terror Radius suffer from inefficiency:

When using an Item, its Depletion rate is increased by 80/90/100 percent.