Siege on Estelminas

From the introduction: You've been travelling without incident for a few days now, and though it's been a while since you've seen a tree trunk scarred by an owlbear or the darting shadows of giant spider between the branches, still there is an ominous feeling in your heart. Everywhere there are small signs that something isn't quite right with the area you've wandered into: the streams that criss-cross the ground here are edged with frost, and every time it rains you think you can feel a few flecks of snow catch your face. Such weather is quite unusual for this time of year, and what’s even more disconcerting is that you can't figure out what might cause such a change. User summary: For 5th - 10th level characters.