Talk to Windcaller Proudhorn at Cenarion Hold in Silithus.
Attention, heroes of the Alliance! The silithid menace has been left unchecked for too long. Unfettered by any real opposition, they've been preparing all this time for a large-scale expansion.
Cenarion Circle forces are gathering in Silithus to take the fight to these wretched creatures and all able-bodied adventurers are hereby called to join us!
Don't wait until it's too late! Aid us in the defense of Azeroth! Report to Windcaller Proudhorn at Cenarion Hold for specific instructions!