Rhadrog has asked you to use the Haerondir Horn in certain places around Haerondir, and to use it to scare nearby curious Orcs.
'Another way we keep those Orcs out of here is with the use of eerie-sounding instruments. Here's one of them: the Haerondir Horn! There's a few places in Haerondir that have excellent acoustics. Go blow the horn in those places, and after that, see if you can find any curious Orcs that have strayed too close. Sneak up behind them, and blow the horn! Keeping the fear in them keeps us safe. I'll admit, it's also a bit of fun, but don't tell Anborn I said that.'
Use the Haerondir Horn at horn-blowing spots in Haerondir.
Curious Orcs can be found outside of Haerondir.
Use the Haerondir Horn to spook curious Orcs who have wandered too close to Haerondir.