If you have been avoiding her for the last several years so as not to witness a great choreographer succumb to self-caricature, you may now safely return for Twyla Tharp’s diamond jubilee concert, on the occasion of her much-deserved Golden Lion Lifetime Achievement Award, courtesy the Venice Biennale. The hour-long Diabelli features the 85-year-old choreographer doing what she does best: variations on variations, as does Beethoven—played live by the precocious pianist Vladimir Rumyantsev. Beethoven’s structure lends the choreographer a game plan; its myriad forms let her play. Diabelli met with acclaim when it premiered in 1998 and only disappeared for lack of funds. As for the European premiere, Slacktide is by all reports the best new work Tharp has done in some time. Her famous style often possesses an underwater bonelessness; with Slacktide, she plays it up and slows it down to mesmerizing effect. Third Coast Percussion brings Philip Glass’s soggy 1993 score Águas da Amazônia to life. Tharp’s new crop of freelance dancers are, like the old crop, outstanding. —Apollinaire Scherr