Just finished this quest so I figured I'd try to provide more detail.
Ambush 1: Right in front of the Ancient Quarry where you received the quest from Alon to clear it out and open the door. You'll be attacked by various people named after birds (I recall Raven, Hawk, and Condor).
Ambush 2: This is past the far north bridge from Gran Soren. The one that Catacombs Rear Passage 2 is at. You'll be attacked by names like Phantom and Ghost.
Ambush 3: Follow the path back towards the Waycastle and take the top road, as if heading to the Mountain Cottage;. It's a small area to the side with a large tree. You'll be attacked by Darkness.
Ambush 4: Just walk the path between Waycastle and Encampment. You'll be attacked by Rouge and someone else, I forget.
Ambush 5: Literally right at the entrance of Cassardis. You'll be attacked by Zero.