After hooking a Survivor, Pop Goes the Weasel activates for the next 35/40/45 seconds:

Performing the Damage Generator Action on a Generator instantly regresses it by -20 percent of its current Progression, after which normal Regression applies.

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.

Your base Terror Radius is increased by 8 meters.

Whenever you are outside of a Chase, your Terror Radius is reduced by 16 metres while your Field of View is increased by 3/5/10 °.
Field of View gains do not stack.

After hooking a Survivor, Pop Goes the Weasel activates for the next 35/40/45 seconds:

Performing the Damage Generator Action on a Generator instantly regresses it by -20 percent of its current Progression, after which normal Regression applies.