I just placed the idol and went to see the Shaman. While crossing the shallow pool, I noticed that the Giant Bat was flying just behind the Shaman's hut. I walked over, stood to one side of the hut, and the bat turned and faced me like it wanted to attack. After that, I killed it with impaling stones. I've need seen it face forwards like this in any other location.

You found the best place to attack The Bat. If someone tries too early, they will find the thing has a nasty bite and can drain you. I generally like to have some Trynnies around when I try to take him on. He also can fly off before the kill so I usually do not bother.

I always try to fight it the first time I saw it. it gives good experience for a party that is still low.