Resolved, shoveling off.

[predikit]

I did something slightly inquisitive, and decided to dig out the circle before stepping in the circle of stones. Now the guardians can't be called! I will have to start over I fear, but just a heads up in case anyone else gets a little dig happy.

[Phitt]

That's strange, I'm pretty sure I did that as well the first time I played. So if you

SpoilerShow

right-click on the horn in your hand while standing in the circle the sound effect comes up yet nothing happens?

[predikit]

*peers suspiciously* I must need to go over the level with a fine tooth comb again, I appear to have missed something.

[JohnWordsworth]

I just did a quick run to this point and I can't reproduce the issue here. Either you've done something strange (which has caused a related issue) or perhaps you've just not quite done the right thing yet .

[petri]

The OP probably assumes that something happens when he steps into the circle.

[predikit]

Quite so, quite so. I was too skittish to go sniffing down the staircase first time I happened upon it, but well, after that it was simplicity itself.