Characterized by reaction, especially opposition to progress or liberalism; extremely conservative.
n. pl. re·ac·tion·ar·ies
An opponent of progress or liberalism; an extreme conservative.
So stop it. If you want to say a reflex save, or instinctive play, say that. It's perfectly fine to say that a move was a reaction. Don't add syllables to a word to turn it into an adjective, it doesn't make you sound smart. It does the opposite.