Known internationally for his inventiveness ­and ingenuity, Dmitry Krymov creates fantastic spectacles of­ operatic ­proportion with the simplest of materials­. Larger-th­an-life puppets, cacophonous dancing pianos, musicians who become actors, actors who become acrobats, and walls that erupt with imagery inhabit a stunning theatrical world that changes in the blink of an eye. One never knows what will happen next in Krymov’s Opus No. 7. Presented in two parts,Genealogy and Shostakovich, it’s about the legacy of oppression of Soviet Jews and artists under Stalin — by turns tender and delicate, comedic and sinister.