I believe both have one-off spells that could disable/KO the other, and Shaman may be quicker to access his medicine bag than Spiral is to dance. That sort of "fastest-gun" scenario aside, if she gets in close, Spiral will best Shaman, and likely keep him too occupied to cast his upper tier spells.
I might give it 7.5/10 to Shaman, but that reverses quickly based on how close they start or how long the fight goes on.