Wrench Lurker 2

From BioShock Wiki

Wrench Lurker is a combat tonic which increases wrench damage by 200% against unaware or shocked opponents. In addition it quiets the user's footsteps. It can be stacked with Wrench Lurker

Game Caption

Only a fool fights fair. When you want to take them down from behind, be smart, use Wrench Lurker Two!

Location

First available for purchase from Gatherer's Garden in Olympus Heights and all subsequent levels.