The bottom of the thaig glows orange with fire and is teeming with darkspawn. That's not unexpected. Whatever is down there, making the song reverberate off the walls, it's their life's work to reach it--and the Wardens would have felt the horde, anyhow, even if it hadn't been logical to expect them to be there. It's a long way down, a way that would require traversing levels of bridges and narrow walkways along the walls of the cavern, and an equally long way up. The vast sea of monsters below won't be a problem (probably, if they leave quickly enough), even though the roar from beneath when the darkspawn sense the new presence above sounds like a battle cry.
The problem is the wave from behind, the direction they entered from--only a tickle, at first, in the head of the Warden nearest the entrance, half-buried beneath the sensation of so many more connected minds down below. But it gets stronger. Quickly.
OOC | This one is GMed. Fill out the form in this post unless you want me to assume I can burn your character's face off.
( the gang tries not to die )