Ambiguous adjective – Having an often intentionally veiled or uncertain meaning. Mystical and ambiguous are semantically related. In some cases you can use "Mystical" instead an adjective "Ambiguous". Nearby Words: ambiguity, ambiguously
Doing In the Scientist: Most of the series is about debunking mystical explanations for things (or at least keeping it very ambiguous), but the final book's climax has a number of elements that could not be plausibly explained as anything other than magic.