How can I get past that thing on the right side of the face screen?

Hint 1 of 9:

You'll need to get it out of its hole first.

Hint 2 of 9:

The name of one of the items shows that it's made to bring the thing out.

Hint 3 of 9:

It's the bait.  Drop it just near the thing's home.  You can find the bait
in the tower just to the right of the door from which you entered.

Hint 4 of 9:

Now you need to find something that will make the troll go away.

Hint 5 of 9:

That troll is highly allergic to water.