The Hope of Erethor
Paraphrased from pages 221-222
The Whispering Wood is a phenomenon whereby the souls of slain elves may merge with the trees of Erethor. While in this state, the souls share information and whisper it to those trained to understand their messages.
When in Erethor, a character who can contact (or be contacted) by the Whisper is able to determine the proximity of others, the direction game has fled, and the presence of danger or out landers. In game terms, this means that an elf (or Elfling) may attempt to communicate with the Whisper as if it were a trapped spirit. The whisper is everywhere throughout the Great Forest and can be contacted anywhere in Erethor with a Wisdom check. Elves make a DC 12 wisdom check. Elfling make a DC 16 Wisdom check. Once the Whisper is contacted, information may be gleaned from it using the normal rules for deciphering its insights and observations (see page 342 below) the Whisper range is of regional awareness is anywhere in Erethor.
Sensing the Whisper is not only an active or even conscious ability and the forest can Whisper to her children at any time. Wisdom check (secretly rolled by DM) determines if the whisper succeeds in contacting the Elf or Elfling characters.
Page 342 paraphrase
If the character can speak to the Whispser (via a shared language – Elfish) it can provide information via cryptic phrases, strange riddles, and esoteric observations.