We cleared the entire scenario without taking one point of damage. 6 PCs and two pets. Not a single one took a point of damage. We got hit with Fascinate and Grappled by a chain. That was it.
The maze was a series of 11? skill checks. I think we failed three times out of 11. Never by enough to trigger a trap or encounter. One PC had a perception of +14 and another had a Survival skill of +11. Needless to say with 5 other PCs assisting we had a minimum of 20 to 28 before adding in the D20 roll.
The fight with the giant leech was a laugh. The environment and setup was great. Our GM spiced that section up with great flavor and role-play. But the leech went down in 2 rounds.
The only part of the adventure that ended being challenging was the water flow chamber. Two PCs got trapped together in the chamber without the wand of Water Breathing.