In that case, why not just make it tap to perform the effect. I wouldn't care if it were playable at the speed of an instant if it tapped. You probably want it to be able to do this ability and also attack, but I think that's gratuitous. Also, why is it a 2/3? Aren't shamans typically wizened elders - the sort of characters that are properly 1/1?
Now that I think about it, even if you make those changes, and definitely now, this card is much better and very similar to a card I already posted,
Priest of Quiacatl.