The phrase "tone setter" refers to a person, thing, or event that establishes the mood, atmosphere, or attitude for a particular situation or group of people. Full definition
While educators recognize the importance of reading, «riting, and «rithmetic, many see the first days of school as tone setters. (qedfoundation.org)
These first two games, especially with the history of last season's disappointment, are very important «tone setters». (justarsenal.com)
Don't get me wrong, I love big fast strong guys and tone setters, but if I am looking for a MLB, they need to have it between the ears since they tend to be the de facto QBs of the defense. (sbnation.com)