From the Anishinabe language.

How so? What role does a shaman play in a pow wow? I've been to one before. It would have been interesting to know.

Nowadays, mostly just the opening & closing ceremonies. However, the original meaning of the word powwow was a gathering where shamans would share insights.

What kind of insights?

Well, I wasn't alive all those centuries ago...I mean I was, but memories from that many reincarnations ago are hard to come by. I'll speculate wisdom gained during vision quests, deep meditation or drug use; medicinal plants that were discovered; maybe a new spell that someone has developed?