The Watcher wounds you with Vile Scream for 10,289 points of Acid.
This npc has MASSIVE DREAD, it is suggested that you get some radiance armour, before fighting it, and acid resist gear/traits.
Going into the room with The Watcher in it, you will get You are wounded for 169 points of Acid damage. So keep in mind, you get damage just for being in the room with this mob, unless you have resist gear.
Locations with maps: The Water-Works Click here for more and bigger maps with filtering options