Dubstep, the kissing cousin of London garage music and the distant progeny of Jamaican dub, has started to make synthesized waves throughout the club scene in the United States. Electronic music that is characterized by the absence of DJ participation and vocals, dubstep has heavy, syncopated bass lines that hit listeners with the concentrated strength and balletic rhythm of a heavyweight boxer (an artful violence that fans happily parry). As a form, dubstep broods, making it a sort of introverted response to the sardonicism of garage. Baltimore DJ Joe Nice deserves much of the credit for dubstep’s successful arrival from England. Nice continues to spread the gospel when he joins the Lotus Camp, a local DJ collective, for the fourth installment of their Kablammo series, Saturday at the Czar Bar.