Those Blood-curdling Screams off in the Distance are Actually....

d12
1. Shriek-bats in a feeding frenzy
2. Courtship hollers of feral halflings
3. Freshly-hatched cockatrice chicks exercising their lungs
4. Rehearsal for sub-humanoid choir at ramshackle temple to their obscene deity
5. Mimic-apes having a laugh
6. Bored and drunk vampires amusing themselves
7. The sounds of an arcane gateway opening up to a hellish nightmare realm
8. Echoes of metal-on-metal from a giant filing the blade on mammoth axe to a slightly-less-dull edge
9. Agonized yelps of new recruits being "branded in" to bandit organization
10. Ogres enjoying a game of Thumbscrew Challenge
11. Capricious wind-spirit that moves continuously further off trail
12. Genuine final vocalizations of doomed monster-attack victims: sure, you could run off to save them but you'd be far, far too late